'\"
'\" Generated from file 'Object\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2014-19 Stefan Sobernig <stefan\&.sobernig@wu\&.ac\&.at>, Gustaf Neumann <gustaf\&.neumann@wu\&.ac\&.at>; available under the Creative Commons Attribution 3\&.0 Austria license (CC BY 3\&.0 AT)\&.
'\"
.TH "nx::Object" 3 2\&.4\&.0 Object "NX API"
.\" The -*- nroff -*- definitions below are for supplemental macros used
.\" in Tcl/Tk manual entries.
.\"
.\" .AP type name in/out ?indent?
.\"	Start paragraph describing an argument to a library procedure.
.\"	type is type of argument (int, etc.), in/out is either "in", "out",
.\"	or "in/out" to describe whether procedure reads or modifies arg,
.\"	and indent is equivalent to second arg of .IP (shouldn't ever be
.\"	needed;  use .AS below instead)
.\"
.\" .AS ?type? ?name?
.\"	Give maximum sizes of arguments for setting tab stops.  Type and
.\"	name are examples of largest possible arguments that will be passed
.\"	to .AP later.  If args are omitted, default tab stops are used.
.\"
.\" .BS
.\"	Start box enclosure.  From here until next .BE, everything will be
.\"	enclosed in one large box.
.\"
.\" .BE
.\"	End of box enclosure.
.\"
.\" .CS
.\"	Begin code excerpt.
.\"
.\" .CE
.\"	End code excerpt.
.\"
.\" .VS ?version? ?br?
.\"	Begin vertical sidebar, for use in marking newly-changed parts
.\"	of man pages.  The first argument is ignored and used for recording
.\"	the version when the .VS was added, so that the sidebars can be
.\"	found and removed when they reach a certain age.  If another argument
.\"	is present, then a line break is forced before starting the sidebar.
.\"
.\" .VE
.\"	End of vertical sidebar.
.\"
.\" .DS
.\"	Begin an indented unfilled display.
.\"
.\" .DE
.\"	End of indented unfilled display.
.\"
.\" .SO ?manpage?
.\"	Start of list of standard options for a Tk widget. The manpage
.\"	argument defines where to look up the standard options; if
.\"	omitted, defaults to "options". The options follow on successive
.\"	lines, in three columns separated by tabs.
.\"
.\" .SE
.\"	End of list of standard options for a Tk widget.
.\"
.\" .OP cmdName dbName dbClass
.\"	Start of description of a specific option.  cmdName gives the
.\"	option's name as specified in the class command, dbName gives
.\"	the option's name in the option database, and dbClass gives
.\"	the option's class in the option database.
.\"
.\" .UL arg1 arg2
.\"	Print arg1 underlined, then print arg2 normally.
.\"
.\" .QW arg1 ?arg2?
.\"	Print arg1 in quotes, then arg2 normally (for trailing punctuation).
.\"
.\" .PQ arg1 ?arg2?
.\"	Print an open parenthesis, arg1 in quotes, then arg2 normally
.\"	(for trailing punctuation) and then a closing parenthesis.
.\"
.\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
.\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
.\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
.\"	# BS - start boxed text
.\"	# ^y = starting y location
.\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
.\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
.\"	# VS - start vertical sidebar
.\"	# ^Y = starting y location
.\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
.\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
.\"	# Special macro to handle page bottom:  finish off current
.\"	# box/sidebar if in box/sidebar mode, then invoked standard
.\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
.\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
.\"	# DE - end display
.de DE
.fi
.RE
.sp
..
.\"	# SO - start of list of standard options
.de SO
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
.\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\*(So manual entry for details on the standard options.
..
.\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
.\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
.\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.\"	# UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
.\"	# QW - apply quotation marks to word
.de QW
.ie '\\*(lq'"' ``\\$1''\\$2
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\$2
..
.\"	# PQ - apply parens and quotation marks to word
.de PQ
.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
.\"" fix emacs highlighting
.el (\\*(lq\\$1\\*(rq\\$2)\\$3
..
.\"	# QR - quoted range
.de QR
.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
..
.\"	# MT - "empty" string
.de MT
.QW ""
..
.BS
.SH NAME
nx::Object \- API reference of the base class in the NX object system
.SH SYNOPSIS
\fBnx::Object\fR \fBcreate\fR \fIobj\fR ?\fB-object-mixins\fR \fImixinSpec\fR? ?\fB-class\fR \fInewClassName\fR? ?\fB-object-filters\fR \fIfilterSpec\fR? ?\fIinitBlock\fR?
.sp
\fBnx::Object\fR \fBnew\fR ?\fB-object-mixins\fR \fImixinSpec\fR? ?\fB-class\fR \fInewClassName\fR? ?\fB-object-filters\fR \fIfilterSpec\fR? ?\fIinitBlock\fR?
.sp
\fIobj\fR ?\fBpublic\fR | \fBprivate\fR | \fBprotected\fR? \fBobject alias\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fImethodName\fR ?\fB-returns\fR \fIvalueChecker\fR? ?\fB-frame\fR \fBobject\fR | \fBmethod\fR? \fIcmdName\fR
.sp
\fIobj\fR \fBcget\fR \fIconfigurationOption\fR
.sp
\fIobj\fR \fBconfigure\fR ?\fIconfigurationOption\fR \fIvalue\fR \&.\&.\&.?
.sp
\fIobj\fR \fBcontains\fR ?-withnew \fItrueFalse\fR? ?-object \fIobjectName\fR? ?-class \fIclassName\fR? \fIcmds\fR
.sp
\fIobj\fR \fBcopy\fR ?\fInewObjectName\fR?
.sp
\fIobj\fR \fBdelete object\fR \fIfeature\fR \fIarg\fR
.sp
\fIobj\fR \fBdestroy\fR
.sp
\fIobj\fR \fBeval\fR \fIarg\fR ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBobject\fR \fBfilters\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject forward\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fImethodName\fR ?\fB-prefix\fR \fIprefixName\fR? ?\fB-frame\fR \fBobject\fR? ?\fB-returns\fR \fIvalueChecker\fR? ?\fB-verbose\fR? ?\fItarget\fR? ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBinfo baseclass\fR
.sp
\fIobj\fR \fBinfo children\fR ?\fB-type\fR \fIclassName\fR? ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo class\fR
.sp
\fIobj\fR \fBinfo has\fR ?\fBmixin\fR | \fBnamespace\fR | \fBtype\fR? ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBinfo lookup\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBinfo name\fR
.sp
\fIobj\fR \fBinfo info\fR ?\fB-asList\fR?
.sp
\fIobj\fR \fBinfo object filters\fR ?\fB-guards\fR? ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo object method\fR \fIoption\fR \fImethodName\fR
.sp
\fIobj\fR \fBinfo object methods\fR ?\fB-callprotection\fR \fIlevel\fR? ?\fB-type\fR \fImethodType\fR? ?\fB-path\fR? ?\fInamePattern\fR?
.sp
\fIobj\fR \fBinfo object mixins\fR ?\fB-guards\fR? ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo object slots\fR ?\fB-type\fR \fIclassName\fR? ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo object variables\fR ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo parent\fR
.sp
\fIobj\fR \fBinfo precedence\fR ?\fB-intrinsic\fR? ?\fIpattern\fR?
.sp
\fIobj\fR \fBinfo variable\fR \fIoption\fR \fIhandle\fR
.sp
\fIobj\fR \fBinfo vars\fR ?\fIpattern\fR?
.sp
\fIobj\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject method\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fIname\fR \fIparameters\fR ?\fB-checkalways\fR? ?\fB-returns\fR \fIvalueChecker\fR? \fIbody\fR
.sp
\fIobj\fR \fBmove\fR \fInewObjectName\fR
.sp
\fIobj\fR \fBobject mixins\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBobject property\fR ?\fB-accessor\fR \fBpublic\fR | \fBprotected\fR | \fBprivate\fR? ?\fB-class\fR \fIclassName\fR? ?\fB-configurable\fR \fItrueFalse\fR? ?\fB-incremental\fR? ?\fB-nocomplain\fR? ?\fB-trace\fR \fBset\fR | \fBget\fR | \fBdefault\fR? \fIspec\fR ?\fIinitBlock\fR?
.sp
\fIobj\fR \fBrequire namespace\fR
.sp
\fIobj\fR \fBrequire\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject method\fR \fImethodName\fR
.sp
\fIobj\fR \fBunknown\fR \fIunknownMethodName\fR ?\fIarg\fR \&.\&.\&.?
.sp
\fIobj\fR \fBuplevel\fR ?\fIlevel\fR? \fIarg1\fR ?\fIarg2\fR \&.\&.\&.?
.sp
\fIobj\fR \fBupvar\fR ?\fIlevel\fR? \fIotherVar1\fR \fIlocalVar1\fR ?\fIotherVar2\fR \fIlocalVar2\fR \&.\&.\&.?
.sp
\fIobj\fR \fBobject variable\fR ?\fB-accessor\fR \fBpublic\fR | \fBprotected\fR | \fBprivate\fR? ?\fB-incremental\fR? ?\fB-class\fR \fIclassName\fR? ?\fB-configurable\fR \fItrueFalse\fR? ?\fB-initblock\fR \fIscript\fR? ?\fB-trace\fR \fBset\fR | \fBget\fR | \fBdefault\fR? ?\fB-nocomplain\fR? \fIspec\fR ?\fIdefaultValue\fR?
.sp
.BE
.SH DESCRIPTION
.PP
\fBnx::Object\fR is the base class of the NX object system\&. All
objects defined in NX are (direct or indirect) instances of this
base class\&. The methods provided by the \fBnx::Object\fR
base class are available to all objects and to all classes defined in
NX\&.
.CS


 +---------+
 | ::nx::* |
 +---------+--------------------------------------Y
 |                                                |
 |  +---------+     instance of     +----------+  |
 |  |         |<\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.|          |  |
 |  |  Class  |                     |  Object  |  |
 |  |         |\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.>|          |  |
 |  +----+----+     subclass of     +-----+----+  |
 |       ^                           ^    ^       |
instance\&.|\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.|\&.\&.\&.\&.|\&.\&.\&.\&.\&.\&.\&./
      of |                           |    |
   +-----+-----+    subclass of      |    | instance
   |           |\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.|    | of
   |   /cls/   |    (by default)          |
   |           |                          |
   +-----------+                          |
         ^                                |
instance |\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.(xor)\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.|
      of |         +-----------+          |
         |\&.\&.\&.\&.\&.\&.\&.\&.\&.|           |\&.\&.\&.\&.\&.\&.\&.\&.\&.\&.|
                   |   /obj/   |
                   |           |
                   +-----------+

.CE
NX allows for creating and for using objects (e\&.g\&. \fIobj\fR) which are
instantiated from the base class \fBnx::Object\fR
directly\&. Typical use cases are singletons and anonymous, inline
objects\&. In such use cases, NX does not require creating an
intermediate application class (e\&.g\&. \fIcls\fR), which specializes the base class
\fBnx::Object\fR by default, beforehand\&.
.PP
Objects (e\&.g\&. \fIobj\fR) which are creating by instantiating a
previously defined application class (e\&.g\&. \fIcls\fR) are indirect
instances of \fBnx::Object\fR\&.
.PP
Direct instances of \fBnx::Object\fR can be created as follows:
.TP
\fBnx::Object\fR \fBcreate\fR \fIobj\fR ?\fB-object-mixins\fR \fImixinSpec\fR? ?\fB-class\fR \fInewClassName\fR? ?\fB-object-filters\fR \fIfilterSpec\fR? ?\fIinitBlock\fR?
.sp
To create a direct instance of \fBnx::Object\fR having an explicit name
\fIobj\fR, use \fBcreate\fR on \fBnx::Object\fR\&. Note that
\fBcreate\fR is defined by \fBnx::Class\fR and is available to \fBnx::Object\fR being
an instance of \fBnx::Class\fR\&. This way, singleton objects can be
created, for example\&.
.TP
\fBnx::Object\fR \fBnew\fR ?\fB-object-mixins\fR \fImixinSpec\fR? ?\fB-class\fR \fInewClassName\fR? ?\fB-object-filters\fR \fIfilterSpec\fR? ?\fIinitBlock\fR?
To create a direct instance of \fBnx::Object\fR having an
automatically assigned, implicit object name, use \fBnew\fR on \fBnx::Object\fR\&. Note
that \fBnew\fR is defined by \fBnx::Class\fR and is available to
\fBnx::Object\fR being an instance of \fBnx::Class\fR\&. Using \fBnew\fR allows
for creating anonymous, inline objects, for example\&.
.PP
The configuration options for direct and indirect instances of \fBnx::Object\fR, which
can be passed when calling \fBcreate\fR and \fBnew\fR, are
documented in the subsequent section\&.
.SH "CONFIGURATION OPTIONS FOR INSTANCES OF NX::OBJECT"
.PP
Configuration options can be used for configuring objects
during their creation by passing the options as non-positional
arguments into calls of \fBnew\fR and \fBcreate\fR (see \fBnx::Class\fR)\&. An
existing object can be queried for its current configuration using
\fBcget\fR and it can be re-configured using \fBconfigure\fR\&. Legal
configuration options are:
.TP
\fB-class\fR ?\fIclassName\fR?
Retrieves the current class of the object or sets the object's class to \fIclassName\fR, if provided\&.
.TP
\fB-object-filters\fR ?\fIfilterMethods\fR?
Retrieves the list of currently active per-object filter methods or sets
a list of per-object filter methods, if \fIfilterMethods\fR is
provided\&.
.TP
\fB-object-mixins\fR ?\fImixinSpecs\fR?
If \fImixinSpecs\fR is not specified, retrieves the list of currently
active per-object mixin specifications\&. If \fImixinSpecs\fR is
specified, sets a list of per-object mixin specifications to become
active\&. mixin classes are returned or set in terms of a list
of mixin specifications\&.
.PP
.SH "METHODS FOR INSTANCES OF NX::OBJECT"
.TP
\fBalias\fR
.RS
.TP
\fIobj\fR ?\fBpublic\fR | \fBprivate\fR | \fBprotected\fR? \fBobject alias\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fImethodName\fR ?\fB-returns\fR \fIvalueChecker\fR? ?\fB-frame\fR \fBobject\fR | \fBmethod\fR? \fIcmdName\fR
Define an alias method for the given object\&. The
resulting method registers a pre-existing Tcl command \fIcmdName\fR
under the (alias) name \fImethodName\fR with the object\&. If \fIcmdName\fR refers
to another \fBmethod\fR, the corresponding argument
should be a valid method handle\&. If a Tcl command (e\&.g\&., a
\fBproc\fR), the argument should be a fully qualified Tcl command
name\&. If aliasing a subcommand (e\&.g\&., \fBarray exists\fR) of a Tcl namespace ensemble (e\&.g\&., \fBarray\fR), \fIcmdName\fR must hold the fully qualified subcommand name (and not the ensemble name of the subcommand)\&.
.sp
As for a regular \fBobject method\fR, \fB-returns\fR
allows for setting a value checker on the values returned by
the aliased command \fIcmdName\fR\&.
.sp
When creating an alias method for
a \fIC-implemented\fR Tcl command (i\&.e\&., command defined using the
Tcl/NX C-API), \fB-frame\fR sets the scope
for variable references used in the aliased command\&. If the provided
value is \fBobject\fR, then variable references will be resolved in the
context of the called object, i\&.e\&., the object upon which the alias method is invoked, as if they were object variables\&. There is no need for using
the colon-prefix notation for identifying object variables\&. If the
value is \fBmethod\fR, then the aliased command will be executed as a regular method call\&. The command is aware of its called-object context; i\&.e\&., it can resolve \fB::nx::self\fR\&. In addition, the alias method has access to the method-call context (e\&.g\&., \fBnx::next\fR)\&. If \fB-frame\fR is omitted, and by default, the variable references will resolve in the context of the caller of the alias method\&.
.sp
To express deprecation of the alias method \fImethodName\fR, set the \fB-deprecated\fR flag\&. Deprecated methods remain usable from client code, but their usage will be signaled to the developer and/or can be tracked using \fB::nsf::deprecated\fR\&. To register \fImethodName\fR with the debugger, set the \fB-debug\fR flag\&.  Entering and exiting a method, which was flagged for debugging, is recorded by calling the redefinable callback procs \fB::nsf::debug::call\fR and \fB::nsf::debug::exit\fR, respectively\&. By default, these callbacks forward to \fB::nsf::log\fR, which can also be customized at the script level\&.
.RE
.TP
\fBcget\fR
.RS
.TP
\fIobj\fR \fBcget\fR \fIconfigurationOption\fR
The method is used to obtain the current value of \fIconfigurationOption\fR for
\fIobj\fR\&. The configuration options
available for querying through \fBcget\fR are determined by the
configurable properties defined by the class hierarchy of \fIobj\fR\&. The
queryable configuration options for \fIobj\fR can be
obtained by calling \fBinfo lookup syntax configure\fR\&. The \fIconfigurationOption\fR can
be set and modified using \fBconfigure\fR\&.
.CS


% nx::Object create obj
::obj
% ::obj info lookup syntax configure
?-object-mixins /mixinreg \&.\&.\&./? ?-class /class/? ?-object-filters /filterreg \&.\&.\&./? ?/__initblock/?
% ::obj cget -class
::nx::Object

.CE
.RE
.TP
\fBconfigure\fR
.RS
.TP
\fIobj\fR \fBconfigure\fR ?\fIconfigurationOption\fR \fIvalue\fR \&.\&.\&.?
This method sets configuration options on an object\&. The configuration
options available for setting on \fIobj\fR are determined by the
configurable properties defined by the class hierarchy of \fIobj\fR\&. The
settable configuration options for \fIobj\fR can be
obtained by calling \fBinfo lookup syntax configure\fR\&. Furthermore, \fBconfigure\fR is
also called during object construction\&. Under object construction, it receives
the arguments passed into calls of \fBcreate\fR and \fBnew\fR\&. Options
set using \fBconfigure\fR can be retrieved using \fBcget\fR\&.
.CS


% nx::Class create Foo {:property x}
::Foo
% Foo create f1 -x 101
::f1
% f1 cget -x
101
% f1 configure -x 200
% f1 cget -x
200

.CE
.RE
.TP
\fBcontains\fR
.RS
.TP
\fIobj\fR \fBcontains\fR ?-withnew \fItrueFalse\fR? ?-object \fIobjectName\fR? ?-class \fIclassName\fR? \fIcmds\fR
This method acts as a builder for nested object structures\&. Object
and class construction statements passed to this method as its last
argument \fIcmds\fR are evaluated in a way so that the receiver object
\fIobj\fR becomes the parent of the newly constructed objects and
classes\&. This is realized by setting explicitly the namespace for
constructing relatively named objects\&. Fully qualified object names in
\fIcmds\fR evade the nesting\&.
.sp
\fB-withnew\fR requests the automatic rescoping of
objects created using \fBnew\fR so that they become nested into the
receiver object \fIobj\fR, rather than being created in the default
namespace for autonamed objects (i\&.e\&., ::nsf)\&. If turned off,
autonamed objects do not become children of \fIobj\fR\&.
.sp
The parent object \fIobjectName\fR to be used instead of \fIobj\fR can be specified
using \fB-object\fR\&. If this explicitly set parent
object does not exist prior to calling \fBcontains\fR, it will be
created on the fly as a direct instance of \fBnx::Object\fR\&. Alternatively,
using \fB-class\fR, a class \fIclassName\fR other
than \fBnx::Object\fR for the on-the-fly creation of \fIobjectName\fR
can be provided\&.
.CS


% nx::Class create Window {
  :contains {
    #
    # Become children of Window, implicitly
    #
    nx::Class create Header; # Window::Header
    nx::Object create Panel; # Window::Panel
  }
  #
  # Explicitly declared a child of Window using [self]
  #
  nx::Class create [self]::Slider; # Window::Slider
  #
  # Fully-qualified objects do not become nested
  #
  nx::Class create ::Door; # ::Door
}
::Window
% ::Window info children
::Window::Panel ::Window::Header ::Window::Slider

.CE
.RE
.TP
\fBcopy\fR
.RS
.TP
\fIobj\fR \fBcopy\fR ?\fInewObjectName\fR?
Creates a full and deep copy of a source object \fIobj\fR\&. The
object's copy features all structural and behavioral properties of the
source object, including object variables, per-object methods, nested
objects, slot objects, namespaces, filters, mixins, and traces\&. The
copy can be named explicitly, if \fInewObjectName\fR is provided,
or it is named automatically (in the spirit of \fBnew\fR of
\fBnx::Class\fR)\&.
.RE
.TP
\fBdelete\fR
.RS
.TP
\fIobj\fR \fBdelete object\fR \fIfeature\fR \fIarg\fR
This method serves as the equivalent to Tcl's \fBrename\fR for
removing structural (properties, variables) and behavioral features
(methods) of the object:
.TP
\fIobj\fR \fBdelete object property\fR \fIpropertyName\fR
.TP
\fIobj\fR \fBdelete object variable\fR \fIvariableName\fR
.TP
\fIobj\fR \fBdelete object method\fR \fImethodName\fR
Removes a property \fIpropertyName\fR, variable \fIvariableName\fR,
and method \fImethodName\fR, respectively, previously defined for the
scope of the object\&.
.sp
\fBdelete object method\fR can be equally used for removing regular methods (see \fBobject method\fR), an alias method (see \fBobject alias\fR), and a forwarder method (see \fBobject forward\fR)\&.
.RE
.TP
\fBdestroy\fR
.RS
.TP
\fIobj\fR \fBdestroy\fR
This method allows for explicitly destructing an object \fIobj\fR,
potentially prior to \fIobj\fR being destroyed by the object system
(e\&.g\&. during the shutdown of the object system upon calling \fBexit\fR):
.CS

[nx::Object new] destroy
.CE
.IP
By providing a custom implementation of \fBdestroy\fR, the
destruction procedure of \fIobj\fR can be customized\&. Typically, once
the application-specific destruction logic has completed, a custom
\fBdestroy\fR will trigger the actual, physical object destruction
via \fBnext\fR\&.
.CS


% [nx::Object create obj {
  :public method destroy {} {
    puts "destroying [self]"
    next; # physical destruction
  }
}] destroy
destroying ::obj

.CE
.IP
A customized object-destruction scheme can be made shared between the instances
of a class, by defining the custom \fBdestroy\fR for an
application class:
.CS


% nx::Class create Foo {
    :method destroy {} {
      puts "destroying [self]"
      next; # physical destruction
    }
}
::Foo
% Foo create f1
::f1
% f1 destroy
destroying ::f1

.CE
.IP
Physical destruction is performed by clearing the in-memory object
storage of \fIobj\fR\&. This is achieved by passing \fIobj\fR into a
call to \fBdealloc\fR provided by \fBnx::Class\fR\&. A near, scripted
equivalent to the C-implemented \fBdestroy\fR provided by \fBnx::Object\fR would look
as follows:
.CS


% Object method destroy {} {
  [:info class] dealloc [self]
}

.CE
.IP
Note, however, that \fBdestroy\fR is protected against
application-level redefinition\&. Trying to evaluate the above script snippet yields:
.CS


refuse to overwrite protected method 'destroy'; derive e\&.g\&. a subclass!

.CE
.IP
A custom \fBdestroy\fR must be provided as a refinement in a
subclass of \fBnx::Object\fR or in a mixin class\&.
.RE
.TP
\fBeval\fR
.RS
.TP
\fIobj\fR \fBeval\fR \fIarg\fR ?\fIarg\fR \&.\&.\&.?
Evaluates a special Tcl script for the scope of \fIobj\fR in the style
of Tcl's \fBeval\fR\&. There are, however, notable differences to the
standard \fBeval\fR: In this script, the colon-prefix notation is available to
dispatch to methods and to access variables of \fIobj\fR\&. Script-local
variables, which are thrown away once the evaluation of the script has
completed, can be defined to store intermediate results\&.
.CS


  % nx::Object create obj {
    :object property {bar 1}
    :public object method foo {x} { return $x }
  }
  ::obj
  % ::obj eval {
    set y [:foo ${:bar}]
  }
  1

.CE
.RE
.TP
\fBfilters\fR
.RS
.TP
\fIobj\fR \fBobject\fR \fBfilters\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
Accesses and modifies the list of methods which are registered as
filters with \fIobj\fR using a specific setter or getter
\fIsubmethod\fR:
.RS
.TP
\fIobj\fR \fBobject\fR \fBfilters add\fR \fIspec\fR ?\fIindex\fR?
Inserts a single filter into the current list of filters of \fIobj\fR\&. Using \fIindex\fR, a position in the existing list of filters for inserting the new filter can be set\&. If
omitted, \fIindex\fR defaults to the list head (0)\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters clear\fR
Removes all filters from \fIobj\fR and returns the list of removed filters\&. Clearing
is equivalent to passing an empty list for \fIfilterSpecList\fR to
\fBobject\fR \fBfilter set\fR\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters delete\fR ?\fB-nocomplain\fR? \fIspecPattern\fR
Removes a single filter from the current list of filters of
\fIobj\fR whose spec matches \fIspecPattern\fR\&. \fIspecPattern\fR can
contain special matching chars (see \fBstring match\fR)\&. \fBobject\fR \fBfilters delete\fR will
throw an error if there is no matching filter, unless
\fB-nocomplain\fR is set\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters get\fR
Returns the list of current filter specifications registered for \fIobj\fR\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters guard\fR \fImethodName\fR ?\fIexpr\fR?
If \fIexpr\fR is specified, registers a guard expression \fIexpr\fR with a filter \fImethodName\fR\&. This requires that the filter \fImethodName\fR has been previously set using \fBobject\fR \fBfilters set\fR or added using
\fBobject\fR \fBfilters add\fR\&. \fIexpr\fR must be a valid Tcl expression (see
\fBexpr\fR)\&. An empty string for \fIexpr\fR will clear the currently registered
guard expression for filter \fImethodName\fR\&.
.sp
If \fIexpr\fR is omitted, returns the guard expression set on the
filter \fImethodName\fR defined for \fIobj\fR\&. If none
is available, an empty string will be returned\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters methods\fR ?\fIpattern\fR?
If \fIpattern\fR is omitted, returns all filter names which are
defined by \fIobj\fR\&. By specifying \fIpattern\fR, the returned
filters can be limited to those whose names match \fIpatterns\fR (see
\fBstring match\fR)\&.
.TP
\fIobj\fR \fBobject\fR \fBfilters set\fR \fIfilterSpecList\fR
\fIfilterSpecList\fR takes a list of filter specs, with each spec being itself either a
one-element or a two-element list: \fImethodName\fR ?-guard \fIguardExpr\fR?\&. \fImethodName\fR identifies
an existing method of \fIobj\fR which becomes
registered as a filter\&. If having three elements, the third
element \fIguardExpr\fR will be stored as a guard expression of the
filter\&. This guard expression must be a valid Tcl expression
(see \fBexpr\fR)\&. \fIexpr\fR is evaluated when \fIobj\fR receives a message to determine whether the
filter should intercept the message\&. Guard expressions
allow for realizing context-dependent or conditional filter
composition\&.
.RE
.IP
Every \fImethodName\fR in a \fIspec\fR must resolve to an existing method in
the scope of the object\&. To
access and to manipulate the list of filters of \fIobj\fR,
\fBcget\fR|\fBconfigure\fR \fB-object-filters\fR can also be used\&.
.RE
.TP
\fBforward\fR
.RS
.TP
\fIobj\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject forward\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fImethodName\fR ?\fB-prefix\fR \fIprefixName\fR? ?\fB-frame\fR \fBobject\fR? ?\fB-returns\fR \fIvalueChecker\fR? ?\fB-verbose\fR? ?\fItarget\fR? ?\fIarg\fR \&.\&.\&.?
Define a forward method for the given object\&. The
definition of a forward method registers a predefined, but
changeable list of forwarder arguments under the (forwarder) name \fImethodName\fR\&. Upon
calling the forward method, the forwarder
arguments are evaluated as a Tcl command call\&. That is, if present, \fItarget\fR
is interpreted as a Tcl command (e\&.g\&., a Tcl \fBproc\fR or an object)
and the remainder of the forwarder arguments \fIarg\fR as arguments passed into
this command\&. The actual method arguments to the invocation of the
forward method itself are appended to the list of forwarder
arguments\&.
If \fItarget\fR is omitted, the value of \fImethodName\fR is
implicitly set and used as \fItarget\fR\&. This way, when providing a
fully-qualified Tcl command name as \fImethodName\fR without \fItarget\fR, the
unqualified \fImethodName\fR (\fBnamespace tail\fR) is used as the
forwarder name; while the fully-qualified one serves as the \fItarget\fR\&.
.sp
As for a regular \fBobject method\fR, \fB-returns\fR allows
for setting a value checker on the values returned by the
resulting Tcl command call\&. When passing \fBobject\fR to \fB-frame\fR, the
resulting Tcl command is evaluated in the context of the object
receiving the forward method call\&. This way, variable names
used in the resulting execution of a command become resolved as
object variables\&.
.sp
To express deprecation of the forward method \fImethodName\fR, set the \fB-deprecated\fR flag\&. Deprecated methods remain usable from client code, but their usage will be signaled to the developer and/or can be tracked using \fB::nsf::deprecated\fR\&. To register \fImethodName\fR with the debugger, set the \fB-debug\fR flag\&.  Entering and exiting a method, which was flagged for debugging, is recorded by calling the redefinable callback procs \fB::nsf::debug::call\fR and \fB::nsf::debug::exit\fR, respectively\&. By default, these callbacks forward to \fB::nsf::log\fR, which can also be customized at the script level\&.
.sp
The list of forwarder arguments \fIarg\fR can contain as its elements
a mix of literal values and placeholders\&. Placeholders are prefixed
with a percent symbol (%) and substituted for concrete values upon
calling the forward method\&. These placeholders allow for
constructing and for manipulating the arguments to be passed into the
resulting command call on the fly:
.RS
.IP \(bu
\fB%method\fR becomes substituted for the name of the forward method, i\&.e\&. \fImethodName\fR\&.
.IP \(bu
\fB%self\fR becomes substituted for the name of the object receiving the call of the forward method\&.
.IP \(bu
\fB%1\fR becomes substituted for the first method argument passed to the call of forward method\&. This requires, in turn, that \fIat least\fR one argument is passed along with the method call\&.
.sp
Alternatively, \fB%1\fR accepts an optional argument \fIdefaults\fR: {\fB%1\fR \fIdefaults\fR}\&.
\fIdefaults\fR must be a valid Tcl list of two elements\&. For the first
element, \fB%1\fR is substituted when there is no first method
argument which can be consumed by \fB%1\fR\&. The second element is
inserted upon availability of a first method argument with the
consumed argument being appended right after the second list
element\&. This placeholder is typically used to define a pair of
getter/setter methods\&.
.IP \(bu
{\fB%@\fR\fIindex\fR \fIvalue\fR} becomes substituted for the
specified \fIvalue\fR at position \fIindex\fR in the
forwarder-arguments list, with \fIindex\fR being either a positive
integer, a negative integer, or the literal value \fBend\fR (such as
in Tcl's \fBlindex\fR)\&. Positive integers specify a list position
relative to the list head, negative integers give a position relative
to the list tail\&. Indexes for positioning placeholders in the definition of a
forward method are evaluated from left to right and should be
used in ascending order\&.
.sp
Note that \fIvalue\fR can be a literal or any of the placeholders
(e\&.g\&., \fB%method\fR, \fB%self\fR)\&. Position prefixes are
exempted, they are evaluated as \fB%\fR\fIcmdName\fR-placeholders in this context\&.
.IP \(bu
{\fB%argclindex\fR \fIlist\fR} becomes substituted for the
\fIn\fRth element of the provided \fIlist\fR , with \fIn\fR
corresponding to the number of method arguments passed to the forward method call\&.
.IP \(bu
\fB%%\fR is substituted for a single, literal percent symbol (%)\&.
.IP \(bu
\fB%\fR\fIcmdName\fR is substituted for the value returned
from executing the Tcl command \fIcmdName\fR\&. To pass arguments to \fIcmdName\fR, the placeholder should be wrapped into a Tcl \fBlist\fR: {\fB%\fR\fIcmdName\fR ?\fIarg\fR \&.\&.\&.?}\&.
.sp
Consider using fully-qualified Tcl command names for \fIcmdName\fR to
avoid possible name conflicts with the predefined placeholders, e\&.g\&.,
\fB%self\fR vs\&. %\fB::nx::self\fR\&.
.RE
.sp
To disambiguate the names of subcommands or methods, which potentially
become called by a forward method, a prefix \fIprefixName\fR
can be set using \fB-prefix\fR\&. This prefix is prepended
automatically to the argument following \fItarget\fR (i\&.e\&., a second
argument), if present\&. If missing, \fB-prefix\fR has no
effect on the forward method call\&.
.sp
To inspect and to debug the conversions performed by the above
placeholders, setting the switch \fB-verbose\fR
will have the command list to be executed (i\&.e\&., after substitution)
printed using \fB::nsf::log\fR (debugging level: \fBnotice\fR) upon
calling the forward method\&.
.RE
.TP
\fBinfo\fR
.RS
.TP
\fIobj\fR \fBinfo baseclass\fR
Returns the base class of \fIobj\fR\&. The base class
is the class from which all NX objects are instantiated
directly or indirectly (typically \fBnx::Object\fR)\&.
.TP
\fIobj\fR \fBinfo children\fR ?\fB-type\fR \fIclassName\fR? ?\fIpattern\fR?
Retrieves the list of nested (or aggregated) objects of \fIobj\fR\&. The
resulting list contains the fully qualified names of the nested
objects\&. If \fB-type\fR is set, only nested objects which are
direct or indirect instances of class \fIclassName\fR are
returned\&. Using \fIpattern\fR, only nested objects whose names match
\fIpattern\fR are returned\&. The \fIpattern\fR string can contain
special matching characters (see \fBstring match\fR)\&. This method
allows for introspecting on \fBcontains\fR\&.
.TP
\fIobj\fR \fBinfo class\fR
Returns the fully qualified name of the current \fBnx::Class\fR of
\fIobj\fR\&. In case of re-classification (see \fBconfigure\fR), the
returned class will be different from the \fBnx::Class\fR from which \fIobj\fR was
originally instantiated using \fBcreate\fR or \fBnew\fR\&.
.TP
\fIobj\fR \fBinfo has\fR ?\fBmixin\fR | \fBnamespace\fR | \fBtype\fR? ?\fIarg\fR \&.\&.\&.?
.RS
.TP
\fIobj\fR \fBinfo has mixin\fR \fIclassName\fR
Verifies whether \fIobj\fR has a given \fBnx::Class\fR \fIclassName\fR registered as a mixin class (returns: \fBtrue\fR) or not (returns: \fBfalse\fR)\&.
.TP
\fIobj\fR \fBinfo has namespace\fR
Checks whether the object has a companion Tcl namespace (returns:
\fBtrue\fR) or not (returns: \fBfalse\fR)\&. The namespace could
have been created using, for example, \fBobject require namespace\fR\&.
.TP
\fIobj\fR \fBinfo has type\fR \fIclassName\fR
Tests whether the \fBnx::Class\fR \fIclassName\fR is a type of the
object (returns: \fBtrue\fR) or not (returns: \fBfalse\fR)\&. That
is, the method checks whether the object is a direct instance of \fIclassName\fR or
an indirect instance of one of the superclasses of \fIclassName\fR\&.
.RE
.TP
\fIobj\fR \fBinfo lookup\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
A collection of submethods to retrieve structural features (e\&.g\&.
configuration options, slot objects) and behavioral features
(e\&.g\&. methods, filters) available for \fIobj\fR from the
perspective of a client to \fIobj\fR\&. Features provided by \fIobj\fR
itself and by the classes in its current linearization list are
considered\&.
.RS
.TP
\fIobj\fR \fBinfo lookup filter\fR \fIname\fR
Returns the method handle for the filter method \fIname\fR, if
currently registered\&. If there is no filter \fIname\fR registered, an
empty string is returned\&.
.TP
\fIobj\fR \fBinfo lookup filters\fR ?\fB-guards\fR? ?\fInamePattern\fR?
Returns the method handles of all filters which are active on \fIobj\fR\&. By
turning on the switch \fB-guards\fR, the corresponding guard
expressions, if any, are also reported for each filter as a three-element list: \fImethodHandle\fR -guard \fIguardExpr\fR\&. The returned filters can be limited to
those whose names match \fInamePattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo lookup method\fR \fIname\fR
Returns the method handle for a method \fIname\fR if a
so-named method can be invoked on \fIobj\fR\&. If there is no method
\fIname\fR, an empty string is returned\&.
.TP
\fIobj\fR \fBinfo lookup methods\fR ?\fInamePattern\fR?
Returns the names of all methods (including aliases and forwarders)
which can be invoked on \fIobj\fR\&. The returned methods can be limited
to those whose names match \fInamePattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo lookup mixins\fR ?\fB-guards\fR? ?\fInamePattern\fR?
Returns the object names of all mixin classes which are
currently active on \fIobj\fR\&. By turning on the switch
\fB-guards\fR, the corresponding guard expressions, if any, are also reported as a
three-element list for each mixin class: \fIclassName\fR
-guard \fIguardExpr\fR\&. The returned mixin classes can be
limited to those whose names match \fInamePattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo lookup parameters\fR \fImethodName\fR ?\fInamePattern\fR?
Returns the parameter specification of the method \fImethodName\fR callable
on \fIobj\fR as a list of parameter names and type specifications\&. The
resulting parameter specification can be limited to those
parameters whose names match \fInamePattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo lookup slots\fR ?\fB-type\fR \fIclassName\fR? ?\fB-source\fR all | application | system? ?\fInamePattern\fR?
Returns the command names of all slot objects responsible for
managing properties, variables, and relations of \fIobj\fR\&. The
returned slot objects can be limited according to any or a
combination of the following criteria: First, slot objects
can be filtered based on their command names matching \fInamePattern\fR
(see \fBstring match\fR)\&. Second, \fB-type\fR
allows one to select slot objects which are instantiated from
a subclass \fIclassName\fR of \fBnx::Slot\fR (default: \fBnx::Slot\fR)
\&. Third, \fB-source\fR restricts slot objects returned
according to their provenance in either the NX \fIsystem\fR classes
or the \fIapplication\fR classes present in the linearization list of
\fIobj\fR (default: \fIall\fR)\&.
.sp
To extract details of each slot object, use the \fBinfo\fR
submethods available for each slot object\&.
.TP
\fIobj\fR \fBinfo lookup syntax\fR \fImethodName\fR ?\fInamePattern\fR?
Returns the method parameters of the method \fImethodName\fR callable
on \fIobj\fR as a concrete-syntax description to be used in
human-understandable messages (e\&.g\&., errors or warnings, documentation
strings)\&. The result can be limited to those parameters matching the
\fInamePattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo lookup variables\fR
Returns the command names of all slot objects responsible for
managing properties and variables of \fIobj\fR, if provided by \fIobj\fR
or the classes in the linearization list of \fIobj\fR\&.
.sp
This is equivalent to calling: \fIobj\fR \fBinfo lookup slots\fR -type ::nx::VariableSlot -source all ?\fInamePattern\fR?\&.
.sp
To extract details of each slot object, use the \fBinfo\fR
submethods available for each slot object\&.
.RE
.TP
\fIobj\fR \fBinfo name\fR
Returns the unqualified name of an object, i\&.e\&., the object name
without any namespace qualifiers\&.
.TP
\fIobj\fR \fBinfo info\fR ?\fB-asList\fR?
Returns the available submethods of the \fBinfo\fR method ensemble for
\fIobj\fR, either as a pretty-printed string or as a
Tcl list (if the switch \fB-asList\fR is set) for further
processing\&.
.TP
\fIobj\fR \fBinfo object filters\fR ?\fB-guards\fR? ?\fIpattern\fR?
If \fIpattern\fR is omitted, returns all filter names which are
defined by \fIobj\fR\&. By turning on the switch \fB-guards\fR, the
corresponding guard expressions, if any, are also
reported along with each filter as a three-element list: \fIfilterName\fR -guard
\fIguardExpr\fR\&. By specifying \fIpattern\fR, the
returned filters can be limited to those whose names match \fIpatterns\fR (see
\fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo object method\fR \fIoption\fR \fImethodName\fR
This introspection submethod provides access to the details
of \fImethodName\fR provided by \fIobj\fR\&. If \fImethodName\fR
is not the name of an existing method, an empty string is returned\&. To
disambiguate between a non-existing method and an empty string as
valid return value (e\&.g\&., for \fBinfo object method args|parameters|args|\&.\&.\&.\fR),
use \fBinfo object method exists\fR\&.
.sp
Permitted values for \fIoption\fR are:
.RS
.IP \(bu
\fBargs\fR returns a list containing the parameter names of
\fImethodName\fR, in order of the method-parameter specification\&.
.IP \(bu
\fBbody\fR returns the body script of \fImethodName\fR\&.
.IP \(bu
\fBcallprotection\fR returns the call-protection level set for \fImethodName\fR; possible values: \fBpublic\fR, \fBprotected\fR, \fBprivate\fR\&.
.IP \(bu
\fBdebug\fR returns 1 if \fImethodName\fR is in debug mode, 0 otherwise\&.
.IP \(bu
\fBdefinition\fR returns a canonical command list which allows for (re-)define \fImethodName\fR\&.
.IP \(bu
\fBdefinitionhandle\fR returns the method handle for a submethod in a method ensemble from the perspective of \fIobj\fR as method provider\&. \fImethodName\fR must contain a complete method path\&.
.IP \(bu
\fBdeprecated\fR returns 1 if \fImethodName\fR is deprecated, 0 otherwise\&.
.IP \(bu
\fBexists\fR returns 1 if there is a \fImethodName\fR provided by \fIobj\fR, returns 0 otherwise\&.
.IP \(bu
\fBhandle\fR returns the method handle for \fImethodName\fR\&.
.IP \(bu
\fBorigin\fR returns the aliased command if \fImethodName\fR is an alias method, or an empty string otherwise\&.
.IP \(bu
\fBparameters\fR returns the parameter specification of \fImethodName\fR as
a list of parameter names and type specifications\&.
.IP \(bu
\fBregistrationhandle\fR returns the method handle for a submethod in a method ensemble from the perspective of the method caller\&. \fImethodName\fR must contain a complete method path\&.
.IP \(bu
\fBreturns\fR gives the type specification defined
for the return value of \fImethodName\fR\&.
.IP \(bu
\fBsubmethods\fR returns the names of all submethods of \fImethodName\fR, if \fImethodName\fR is a method ensemble\&. Otherwise, an empty string is returned\&.
.IP \(bu
\fBsyntax\fR returns the method parameters of \fImethodName\fR as a
concrete-syntax description to be used in human-understandable
messages (e\&.g\&., errors or warnings, documentation strings)\&.
.IP \(bu
\fBtype\fR returns whether \fImethodName\fR is a \fIscripted\fR method, an \fIalias\fR method, a \fIforwarder\fR method, or a \fIsetter\fR method\&.
.RE
.TP
\fIobj\fR \fBinfo object methods\fR ?\fB-callprotection\fR \fIlevel\fR? ?\fB-type\fR \fImethodType\fR? ?\fB-path\fR? ?\fInamePattern\fR?
Returns the names of all methods defined by \fIobj\fR\&. Methods
covered include those defined using \fBobject alias\fR
and \fBobject forward\fR\&. The returned methods can be limited
to those whose names match \fInamePattern\fR (see \fBstring match\fR)\&.
.sp
By setting \fB-callprotection\fR, only methods of a certain call protection \fIlevel\fR (\fBpublic\fR, \fBprotected\fR, or \fBprivate\fR) will be returned\&. Methods of a specific type can be requested using \fB-type\fR\&. The recognized values for \fImethodType\fR are:
.RS
.IP \(bu
\fBscripted\fR denotes methods defined using \fBobject\fR \fBmethod\fR;
.IP \(bu
\fBalias\fR denotes alias methods defined using \fBobject\fR \fBalias\fR;
.IP \(bu
\fBforwarder\fR denotes forwarder methods defined using \fBobject\fR \fBforward\fR;
.IP \(bu
\fBsetter\fR denotes methods defined using \fB::nsf::setter\fR;
.IP \(bu
\fBall\fR returns methods of any type, without restrictions (also the default value);
.RE
.TP
\fIobj\fR \fBinfo object mixins\fR ?\fB-guards\fR? ?\fIpattern\fR?
If \fIpattern\fR is omitted, returns the object names of the mixin classes which
extend \fIobj\fR directly\&. By turning on the switch \fB-guards\fR,
the corresponding guard expressions, if any, are also
reported along with each mixin as a three-element list: \fIclassName\fR
-guard \fIguardExpr\fR\&. The returned mixin classes can be limited to those whose names
match \fIpatterns\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo object slots\fR ?\fB-type\fR \fIclassName\fR? ?\fIpattern\fR?
If \fIpattern\fR is not specified, returns the object names of all slot objects defined by \fIobj\fR\&. The returned slot objects can be limited according to any or a
combination of the following criteria: First, slot objects
can be filtered based on their command names matching \fIpattern\fR (see \fBstring
match\fR)\&. Second, \fB-type\fR allows one to select
slot objects which are instantiated from a subclass \fIclassName\fR of \fBnx::Slot\fR (default: \fBnx::Slot\fR)\&.
.TP
\fIobj\fR \fBinfo object variables\fR ?\fIpattern\fR?
If \fIpattern\fR is omitted, returns the object names of all slot objects provided
by \fIobj\fR which are responsible for managing properties and variables of \fIobj\fR\&. Otherwise,
only slot objects whose names match \fIpattern\fR are
returned\&.
.sp
This is equivalent to calling: \fIobj\fR \fBinfo object slots\fR \fB-type\fR \fB::nx::VariableSlot\fR \fIpattern\fR\&.
.sp
To extract details of each slot object, use the \fBinfo\fR
submethods available for each slot object\&.
.TP
\fIobj\fR \fBinfo parent\fR
Returns the fully qualified name of the parent object of \fIobj\fR, if
any\&. If there is no parent object, the name of the Tcl
namespace containing \fIobj\fR (e\&.g\&. "::") will be reported\&.
.TP
\fIobj\fR \fBinfo precedence\fR ?\fB-intrinsic\fR? ?\fIpattern\fR?
Lists the classes from which \fIobj\fR inherits structural (e\&.g\&.
properties) and behavioral features (e\&.g\&. methods) and methods, in
order of the linearization scheme in NX\&. By setting the
switch \fB-intrinsic\fR, only classes which participate in
superclass/subclass relationships (i\&.e\&., intrinsic classes) are
returned\&. If a \fIpattern\fR is provided only classes whose
names match \fIpattern\fR are returned\&. The \fIpattern\fR string can
contain special matching characters (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBinfo variable\fR \fIoption\fR \fIhandle\fR
Retrieves selected details about a variable represented by the given
\fIhandle\fR\&. A \fIhandle\fR can be obtained by querying \fIobj\fR using
\fBinfo object variables\fR and \fBinfo lookup variables\fR\&.
Valid values for \fIoption\fR are:
.RS
.IP \(bu
\fBname\fR returns the variable name\&.
.IP \(bu
\fBparameter\fR returns a canonical parameter specification
eligible to (re-)define the given variable (e\&.g\&. using \fBobject variable\fR) in a new context\&.
.IP \(bu
\fBdefinition\fR returns a canonical representation of the definition command used to create the variable in its current configuration\&.
.RE
.TP
\fIobj\fR \fBinfo vars\fR ?\fIpattern\fR?
Yields a list of Tcl variable names created and defined for the scope of
\fIobj\fR, i\&.e\&., object variables\&. The list can be limited to object variables whose names
match \fIpattern\fR\&. The \fIpattern\fR string can contain special
matching characters (see \fBstring match\fR)\&.
.RE
.TP
\fBmethod\fR
.RS
.TP
\fIobj\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject method\fR ?\fB-debug\fR? ?\fB-deprecated\fR? \fIname\fR \fIparameters\fR ?\fB-checkalways\fR? ?\fB-returns\fR \fIvalueChecker\fR? \fIbody\fR
Defines a scripted method \fImethodName\fR for the scope of the object\&. The
method becomes part of the object's signature interface\&. Besides
a \fImethodName\fR, the method definition specifies
the method \fIparameters\fR and a method \fIbody\fR\&.
.sp
\fIparameters\fR accepts a Tcl \fBlist\fR containing an arbitrary
number of non-positional and positional parameter definitions\&. Each parameter
definition comprises a parameter name, a parameter-specific value checker, and
parameter options\&.
.sp
The \fIbody\fR contains the method implementation as a script
block\&. In this body script, the colon-prefix notation is available to
denote an object variable and a self call\&. In addition, the
context of the object receiving the method call (i\&.e\&., the message)
can be accessed (e\&.g\&., using \fBnx::self\fR) and the call stack can be
introspected (e\&.g\&., using \fBnx::current\fR)\&.
.sp
Optionally, \fB-returns\fR allows for setting a value checker on
values returned by the method implementation\&. By setting
the switch \fB-checkalways\fR, value checking on
arguments and return value is guaranteed to be performed, even if
value checking is temporarily disabled; see \fBnx::configure\fR)\&.
.sp
To express deprecation of the method \fIname\fR, set the \fB-deprecated\fR flag\&. Deprecated methods remain usable from client code, but their usage will be signaled to the developer and/or can be tracked using \fB::nsf::deprecated\fR\&. To register \fIname\fR with the debugger, set the \fB-debug\fR flag\&. Entering and exiting a method, which was flagged for debugging, is recorded by calling the redefinable callback procs \fB::nsf::debug::call\fR and \fB::nsf::debug::exit\fR, respectively\&. By default, these callbacks forward to \fB::nsf::log\fR, which can also be customized at the script level\&.
.sp
A method closely resembles a Tcl \fBproc\fR, but it differs in some
important aspects: First, a method can define non-positional
parameters and value checkers on arguments\&. Second, the script
implementing the method body can contain object-specific notation and
commands (see above)\&. Third, method calls \fIcannot\fR be intercepted
using Tcl \fBtrace\fR\&. Note that an existing Tcl \fBproc\fR can be
registered as an alias method with the object (see
\fBobject alias\fR)\&.
.RE
.TP
\fBmove\fR
.RS
.TP
\fIobj\fR \fBmove\fR \fInewObjectName\fR
Effectively renames an object\&. First, the source object \fIobj\fR is
cloned into a target object \fInewObjectName\fR using \fBcopy\fR\&. Second,
the source object \fIobj\fR is destroyed by invoking \fBdestroy\fR\&.
\fBmove\fR is also called internally when \fBrename\fR is
performed for a Tcl command representing an object\&.
.RE
.TP
\fBmixins\fR
.RS
.TP
\fIobj\fR \fBobject mixins\fR \fIsubmethod\fR ?\fIarg\fR \&.\&.\&.?
Accesses and modifies the list of mixin classes of
\fIobj\fR using a specific setter or getter \fIsubmethod\fR:
.RS
.TP
\fIobj\fR \fBobject\fR \fBmixins add\fR \fIspec\fR ?\fIindex\fR?
Inserts a single mixin class into the current list of mixin classes of \fIobj\fR\&. Using \fIindex\fR, a position in the existing list of mixin classes for inserting the new mixin class can be set\&. If
omitted, \fIindex\fR defaults to the list head (0)\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins classes\fR ?\fIpattern\fR?
If \fIpattern\fR is omitted, returns the object names of the mixin classes which
extend \fIobj\fR directly\&. By specifying \fIpattern\fR, the returned mixin classes can
be limited to those whose names match \fIpattern\fR (see \fBstring match\fR)\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins clear\fR
Removes all mixin classes from \fIobj\fR and returns the list of removed mixin classes\&. Clearing is equivalent to passing an empty list for \fImixinSpecList\fR to
\fBobject\fR \fBmixins set\fR\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins delete\fR ?\fB-nocomplain\fR? \fIspecPattern\fR
Removes a mixin class from a current list of mixin classes of \fIobj\fR whose spec matches \fIspecPattern\fR\&. \fIspecPattern\fR can contain special matching chars (see \fBstring match\fR)\&. \fBobject\fR \fBmixins delete\fR will throw an error if there is no matching mixin class, unless \fB-nocomplain\fR is set\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins get\fR
Returns the list of current mixin specifications\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins guard\fR \fIclassName\fR ?\fIexpr\fR?
If \fIexpr\fR is specified, a guard expression \fIexpr\fR is registered with the mixin class \fIclassName\fR\&. This requires that the corresponding mixin class \fIclassName\fR has been previously set using \fBobject\fR \fBmixins set\fR or added using \fBobject\fR \fBmixins add\fR\&. \fIexpr\fR must be a valid Tcl expression (see
\fBexpr\fR)\&. An empty string for \fIexpr\fR will clear the currently registered
guard expression for the mixin class \fIclassName\fR\&.
.sp
If \fIexpr\fR is not specified, returns the active guard
expression\&. If none is available, an empty string will be returned\&.
.TP
\fIobj\fR \fBobject\fR \fBmixins set\fR \fImixinSpecList\fR
\fImixinSpecList\fR represents a list of mixin class specs, with each spec being itself either a one-element or a three-element list: \fIclassName\fR ?-guard \fIguardExpr\fR?\&. If
having one element, the element will be considered the \fIclassName\fR
of the mixin class\&. If having three elements, the third
element \fIguardExpr\fR will be stored as a guard expression of the
mixin class\&. This guard expression will be evaluated using
\fBexpr\fR when \fIobj\fR receives a message to determine if the mixin
is to be considered during method dispatch or not\&. Guard expressions
allow for realizing context-dependent or conditional mixin
composition\&.
.RE
.IP
At the time of setting the mixin relation, that is, calling \fBobject\fR \fBmixins\fR, every
\fIclassName\fR as part of a spec must be an existing instance of \fBnx::Class\fR\&. To
access and to manipulate the list of mixin classes of \fIobj\fR,
\fBcget\fR|\fBconfigure\fR \fB-object-mixins\fR can also be used\&.
.RE
.TP
\fB__object_configureparameter\fR
.RS
.TP
\fIobj\fR \fB__object_configureparameter\fR
Computes and returns the configuration options available for \fIobj\fR, to be consumed as method-parameter specification by \fBconfigure\fR\&.
.RE
.TP
\fBproperty\fR
.RS
.TP
\fIobj\fR \fBobject property\fR ?\fB-accessor\fR \fBpublic\fR | \fBprotected\fR | \fBprivate\fR? ?\fB-class\fR \fIclassName\fR? ?\fB-configurable\fR \fItrueFalse\fR? ?\fB-incremental\fR? ?\fB-nocomplain\fR? ?\fB-trace\fR \fBset\fR | \fBget\fR | \fBdefault\fR? \fIspec\fR ?\fIinitBlock\fR?
Defines a property for the scope of the object\&. The \fIspec\fR provides
the property specification as a \fBlist\fR holding at least one
element or, maximum, two elements:
\fIpropertyName\fR?\fB:\fR\fItypeSpec\fR? ?\fIdefaultValue\fR?\&. The \fIpropertyName\fR is also used as to form the names of the getter/setter methods,
if requested (see \fB-accessor\fR)\&. It
is, optionally, equipped with a \fItypeSpec\fR following a colon
delimiter which specifies a value checker for the values
which become assigned to the property\&. The second, optional element
sets a \fIdefaultValue\fR for this property\&.
.sp
If \fB-accessor\fR is set, a property will provide for different
getter and setter methods:
.RS
.TP
\fIobj\fR \fIpropertyName\fR \fBexists\fR
Returns 1 if the value store of \fIpropertyName\fR (e\&.g\&., an object
variable) exists and has been given a value, returns 0 otherwise\&.
.TP
\fIobj\fR \fIpropertyName\fR \fBset\fR \fIvalue\fR
Sets the property \fIpropertyName\fR to \fIvalue\fR\&.
.TP
\fIobj\fR \fIpropertyName\fR \fBget\fR
Returns the current value of property \fIpropertyName\fR\&.
.TP
\fIobj\fR \fIpropertyName\fR \fBunset\fR
Removes the value store of \fIpropertyName\fR (e\&.g\&., an object variable), if existing\&.
.RE
.IP
The option value passed along \fB-accessor\fR sets the level of
call protection for the generated getter and setter methods: \fBpublic\fR,
\fBprotected\fR, or \fBprivate\fR\&. By default, no getter and setter
methods are created\&.
.sp
Turning on the switch \fB-incremental\fR provides a refined
setter interface to the value managed by the property\&. First,
setting \fB-incremental\fR implies requesting \fB-accessor\fR
(set to \fBpublic\fR by default, if not specified
explicitly)\&. Second, the managed value will be considered a valid Tcl
list\&. A multiplicity of \fB1\&.\&.*\fR is set by default, if not
specified explicitly as part of \fIspec\fR\&. Third, to
manage this list value element-wise (\fIincrementally\fR), two
additional setter methods become available:
.RS
.TP
\fIobj\fR \fIpropertyName\fR \fBadd\fR \fIelement\fR ?\fIindex\fR?
Adding \fIelement\fR to the managed list value, at the list position given by \fIindex\fR (by default: 0)\&.
.TP
\fIobj\fR \fIpropertyName\fR \fBdelete\fR ?\fB-nocomplain\fR? \fIelementPattern\fR
Removing the first occurrence of an element from the managed list
value which matches \fIelementPattern\fR\&. \fIelementPattern\fR can
contain matching characters (see \fBstring match\fR)\&. An error will
be thrown if there is no match, unless \fB-nocomplain\fR is set\&.
.RE
.sp
By setting \fB-configurable\fR to \fBtrue\fR (the default), the
property can be accessed and modified through \fBcget\fR and
\fBconfigure\fR, respectively\&. If \fBfalse\fR, no configuration option
will become available via \fBcget\fR and \fBconfigure\fR\&.
.sp
If neither \fB-accessor\fR nor \fB-configurable\fR are
requested, the value managed by the property will have to be accessed
and modified directly\&. If the property manages an object variable, its
value will be readable and writable using \fBset\fR and \fBeval\fR\&.
.sp
The \fB-trace\fR option causes certain slot methods to be executed whenever \fBget\fR, \fBset\fR, or \fBdefault\fR operations are invoked on the property:
.RS
.IP \(bu
\fBset\fR: \fIslot\fR \fBvalue=set\fR \fIobj\fR \fIpropertyName\fR \fIvalue\fR
.IP \(bu
\fBget\fR: \fIslot\fR \fBvalue=get\fR \fIobj\fR \fIpropertyName\fR
.IP \(bu
\fBdefault\fR: \fIslot\fR \fBvalue=default\fR \fIobj\fR \fIpropertyName\fR
.RE
.sp
A property becomes implemented by a slot object under any of the following conditions:
.RS
.IP \(bu
\fB-configurable\fR equals \fBtrue\fR (by default)\&.
.IP \(bu
\fB-accessor\fR is one of \fBpublic\fR, \fBprotected\fR, or \fBprivate\fR\&.
.IP \(bu
\fB-incremental\fR is turned on\&.
.IP \(bu
\fIinitBlock\fR is a non-empty string\&.
.RE
.IP
Assuming default settings, every property is realized by a
slot object\&.
.sp
Provided a slot object managing the property is to be
created, a custom class \fIclassName\fR from which this slot object is
to be instantiated can be set using \fB-class\fR\&. The
default value is \fB::nx::VariableSlot\fR\&.
.sp
The last argument \fIinitBlock\fR accepts an optional Tcl script which is passed into
the initialization procedure (see \fBconfigure\fR) of the property's slot object\&. See
also \fB\fIinitBlock\fR for \fBcreate\fR and \fBnew\fR\fR\&.
.sp
By default, the property will ascertain that no (potentially)
pre-existing and equally named object variable will be overwritten
when defining the property\&. In case of a conflict, an error exception
is thrown:
.CS


% Object create obj { set :x 1 }
::obj
% ::obj object property {x 2}
object ::obj has already an instance variable named 'x'

.CE
.IP
If the switch \fB-nocomplain\fR is on, this check is omitted (continuing the above example):
.CS


% ::obj object property -nocomplain {x 2}
% ::obj eval {set :x}
2

.CE
.RE
.TP
\fBrequire\fR
.RS
.TP
\fIobj\fR \fBrequire namespace\fR
Create a Tcl namespace named after the object \fIobj\fR\&. All object
variables become available as namespace variables\&.
.TP
\fIobj\fR \fBrequire\fR ?\fBpublic\fR | \fBprotected\fR | \fBprivate\fR? \fBobject method\fR \fImethodName\fR
Attempts to register a method definition made available using \fB::nsf::method::provide\fR under
the name \fImethodName\fR with \fIobj\fR \&. The registered
method is subjected to default call protection (\fBprotected\fR), if
not set explicitly\&.
.RE
.TP
\fBunknown\fR
.RS
.TP
\fIobj\fR \fBunknown\fR \fIunknownMethodName\fR ?\fIarg\fR \&.\&.\&.?
This method is called implicitly whenever an unknown method is invoked\&.
\fIunknownMethodName\fR indicates the unresolvable method name,
followed by the remainder of the original argument vector as a number
of \fIarg\fR of the calling method invocation\&.
.RE
.TP
\fBuplevel\fR
.RS
.TP
\fIobj\fR \fBuplevel\fR ?\fIlevel\fR? \fIarg1\fR ?\fIarg2\fR \&.\&.\&.?
Evaluate a script or a command at a different stack-frame
level\&. The command behaves in essence like Tcl's \fBuplevel\fR, but can
be used to achieve identical results when filters or mixins are
registered\&.
.RS
.IP \(bu
If the \fIlevel\fR specifier is omitted, \fBuplevel\fR
will skip any auxiliary frames added to the stack by active
filters and mixins\&. The resulting stack-frame level
corresponds to the callinglevel as indicated by \fBnx::current\fR\&. In
this case method \fBuplevel\fR can be used to evaluate the command
in the next enclosing procedure call, i\&.e\&., a frame corresponding to a
proc, method, or apply call, while skipping frames of filters and
mixins\&.
.IP \(bu
If the \fIlevel\fR specifier is provided (relative, or
absolute), \fBuplevel\fR will execute the command in the
stack-frame level\&. In such cases, method \fBuplevel\fR
behaves like Tcl's \fBuplevel\fR command\&.
.RE
.CS


  % nx::Object create ::obj
  ::obj
  % ::obj public object method foo {varName} {
      :uplevel set $varName 1; return
  }
  ::obj::foo
  % namespace eval ::ns1 {
       ::obj foo BAR
  }
  % namespace eval ::ns1 {
      info exists BAR
  }
  1

.CE
.RE
.IP
Note, in the example above, \fBuplevel\fR is guaranteed to
resolve to the calling context of \fBfoo\fR (ns1) despite
mixins and filters being (potentially) registered on \fBobj\fR\&.
.TP
\fBupvar\fR
.RS
.TP
\fIobj\fR \fBupvar\fR ?\fIlevel\fR? \fIotherVar1\fR \fIlocalVar1\fR ?\fIotherVar2\fR \fIlocalVar2\fR \&.\&.\&.?
Links one or more local variables to variables defined in other
scopes (namespaces, objects, call frames)\&.
The command behaves in essence like Tcl's \fBupvar\fR, but can
be used to achieve identical results when filters or mixins are
registered\&.
.RS
.IP \(bu
If the \fIlevel\fR specifier is omitted, \fBupvar\fR
will skip any auxiliary frames added to the stack by active filters and mixins\&. The
resulting stack-frame level corresponds to the callinglevel
as indicated by \fBnx::current\fR\&. Therefore, method \fBupvar\fR gives
access to the next enclosing procedure call, i\&.e\&., a frame
corresponding to a proc, method, or apply call, while skipping
frames of filters and mixins\&.
.IP \(bu
If the \fIlevel\fR specifier is provided (relative, or
absolute), \fBupvar\fR will link into the requested
stack-frame level\&. In these cases, method \fBupvar\fR
behaves like Tcl's  \fBupvar\fR command\&.
.RE
.CS


  % nx::Object create ::obj
  ::obj
  % ::obj public object method foo {varName} {
      :upvar $varName x; set x 1; return
  }
  ::obj::foo
  % namespace eval ::ns1 {
       ::obj foo BAR
  }
  % namespace eval ::ns1 {
      info exists BAR
  }
  1

.CE
.RE
.IP
Note, in the example above, \fBupvar\fR is guaranteed to
resolve to the calling context of \fBfoo\fR (ns1) despite
mixins and filters being (potentially) registered on \fBobj\fR\&.
.TP
\fBvariable\fR
.RS
.TP
\fIobj\fR \fBobject variable\fR ?\fB-accessor\fR \fBpublic\fR | \fBprotected\fR | \fBprivate\fR? ?\fB-incremental\fR? ?\fB-class\fR \fIclassName\fR? ?\fB-configurable\fR \fItrueFalse\fR? ?\fB-initblock\fR \fIscript\fR? ?\fB-trace\fR \fBset\fR | \fBget\fR | \fBdefault\fR? ?\fB-nocomplain\fR? \fIspec\fR ?\fIdefaultValue\fR?
Defines a variable for the scope of the object\&. The \fIspec\fR provides
the variable specification: \fIvariableName\fR?\fB:\fR\fItypeSpec\fR?\&. The
\fIvariableName\fR will be used to name the underlying Tcl variable
and the getter/setter methods, if requested (see \fB-accessor\fR)\&.
\fIspec\fR is optionally equipped with a \fItypeSpec\fR following a colon
delimiter which specifies a value checker for the values
managed by the variable\&. Optionally, a \fIdefaultValue\fR can
be defined\&.
.sp
If \fB-accessor\fR is set explicitly, a variable will
provide for getter and setter methods:
.RS
.TP
\fIobj\fR \fIvariableName\fR \fBexists\fR
Returns 1 if the value store of \fIvariableName\fR (e\&.g\&., an object
variable) exists and has been given a value, returns 0 otherwise\&.
.TP
\fIobj\fR \fIvariableName\fR \fBset\fR \fIvarValue\fR
Sets \fIvariableName\fR to \fIvarValue\fR\&.
.TP
\fIobj\fR \fIvariableName\fR \fBget\fR
Returns the current value of \fIvariableName\fR\&.
.TP
\fIobj\fR \fIvariableName\fR \fBunset\fR
Removes \fIvariableName\fR, if existing, underlying the property\&.
.RE
.IP
The option value passed along \fB-accessor\fR sets the level of
call protection for the getter and setter methods: \fBpublic\fR,
\fBprotected\fR, or \fBprivate\fR\&. By default, no getter and setter
methods are created\&.
.sp
Turning on the switch \fB-incremental\fR provides a refined
setter interface to the value managed by the variable\&. First,
setting \fB-incremental\fR implies requesting \fB-accessor\fR
(\fBpublic\fR by default, if not specified
explicitly)\&. Second, the managed value will be considered a valid Tcl
list\&. A multiplicity of \fB1\&.\&.*\fR is set by default, if not
specified explicitly as part of \fIspec\fR (see above)\&. Third, to
manage this list value element-wise (\fIincrementally\fR), two
additional setter operations become available:
.RS
.TP
\fIobj\fR \fIvariableName\fR \fBadd\fR \fIelement\fR ?\fIindex\fR?
Adding \fIelement\fR to the managed list value, at the list position given by \fIindex\fR (by default: 0)\&.
.TP
\fIobj\fR \fIvariableName\fR \fBdelete\fR ?\fB-nocomplain\fR? \fIelementPattern\fR
Removing the first occurrence of an element from the managed list
value which matches \fIelementPattern\fR\&. \fIelementPattern\fR can
contain matching characters (see \fBstring match\fR)\&. An error will
be thrown if there is no match, unless \fB-nocomplain\fR is set\&.
.RE
.sp
By setting \fB-configurable\fR to \fBtrue\fR, the variable can be
accessed and modified via \fBcget\fR and \fBconfigure\fR,
respectively\&. If \fBfalse\fR (the default), the interface based on \fBcget\fR and
\fBconfigure\fR will not become available\&. In this case, and provided that
\fB-accessor\fR is set, the variable can be accessed and modified via
the getter/setter methods\&. Alternatively, the underlying Tcl variable, which
is represented by the variable, can always be accessed and modified
directly, e\&.g\&., using \fBeval\fR\&. By default, \fB-configurable\fR is
\fBfalse\fR\&.
.sp
The \fB-trace\fR option causes certain slot methods to be executed whenever \fBget\fR, \fBset\fR, or \fBdefault\fR operations are invoked on the variable:
.RS
.IP \(bu
\fBset\fR: \fIslot\fR \fBvalue=set\fR \fIobj\fR \fIvariableName\fR \fIvalue\fR
.IP \(bu
\fBget\fR: \fIslot\fR \fBvalue=get\fR \fIobj\fR \fIvariableName\fR
.IP \(bu
\fBdefault\fR: \fIslot\fR \fBvalue=default\fR \fIobj\fR \fIvariableName\fR
.RE
.sp
A variable becomes implemented by a slot object under any of the following conditions:
.RS
.IP \(bu
\fB-configurable\fR equals \fBtrue\fR\&.
.IP \(bu
\fB-accessor\fR is one of \fBpublic\fR, \fBprotected\fR, or \fBprivate\fR\&.
.IP \(bu
\fB-incremental\fR is turned on\&.
.IP \(bu
\fB-initblock\fR is a non-empty string\&.
.RE
.IP
Provided a slot object managing the variable is to be
created, a custom class \fIclassName\fR from which this slot object is
to be instantiated can be set using \fB-class\fR\&. The
default value is \fB::nx::VariableSlot\fR\&.
.sp
Using \fB-initblock\fR, an optional Tcl \fIscript\fR can be defined which becomes passed into
the initialization procedure (see \fBconfigure\fR) of the variable's slot object\&. See
also \fB\fIinitBlock\fR for \fBcreate\fR and \fBnew\fR\fR\&.
.sp
By default, the variable will ascertain that a
pre-existing and equally named object variable will not be overwritten
when defining the variable\&. In case of a conflict, an error exception
is thrown:
.CS


% Object create obj { set :x 1 }
::obj
% ::obj object variable x 2
object ::obj has already an instance variable named 'x'

.CE
.IP
If the switch \fB-nocomplain\fR is on, this check is omitted (continuing the above example):
.CS


% ::obj object variable -nocomplain x 2
% ::obj eval {set :x}
2

.CE
.RE
.PP
.SH "OBJECT SELF-REFERENCE"
Objects are naturally recursive, with methods of an object \fB::obj\fR
frequently invoking other methods in the same object \fB::obj\fR and
accessing \fB::obj\fR's object variables\&. To represent these
self-references effectively in method bodies, and depending on the
usage scenario, NX offers two alternative notations for self-references: one based on a
special-purpose syntax token ("colon prefix"), the other based on the
command \fBnx::current\fR\&.
.PP
Both, the colon-prefix notation and
\fBnx::current\fR, may be used only in method bodies and scripts
passed to \fBeval\fR\&. If they appear anywhere else, an error will be
reported\&.
There are three main use cases for self-references:
.IP [1]
As a \fIplaceholder\fR for the currently active object, \fBnx::current\fR
can be used to retrieve the object name\&.
.IP [2]
Reading and writing \fIobject variables\fR directly (i\&.e\&. without getter/setter methods in place) require the use
of variable names carrying the prefix \fB:\fR ("colon-prefix
notation")\&. Internally, colon-prefixed variable names are processed
using Tcl's variable resolvers\&. Alternatively, one can provide for getter/setter methods for object variables (see \fBproperty\fR and \fBvariable\fR)\&.
.IP [3]
\fISelf-referential method calls\fR can be defined via
prefixing (\fB:\fR) the method names or, alternatively, via \fBnx::current\fR\&. Internally,
colon-prefixed method names are processed using Tcl's command
resolvers\&. The colon-prefix notation is recommended, also because it
has a (slight) performance advantage over \fBnx::current\fR which
requires two rather than one command evaluation per method call\&.
.PP
See the following listing for some examples corresponding to use cases 1--3:
.CS


  Object create ::obj {
    # 1) print name of currently active object ('::obj')
    puts [current];
    # 2) object variables
    set :x 1; :object variable y 2;
    :public object method print {} {
      # 2\&.a) method-local variable
      set z 3;
      # 2\&.b) variable substitution using '$' and ':'
      puts ${:x}-${:y}-$z;
      # 2\&.c) reading variables using 'set'
      puts [set :x]-[set :y]-[set z];
      # 2\&.d) writing variables using 'set', 'incr', \&.\&.\&.
      set :x 1; incr :y;
    }
    :public object method show {} {
      # 3\&.a) self-referential method call using ':'
      :print;
      # 3\&.b) self-referential method call using 'nx::current'
      [current] print;
      # 3\&.c) self-referential method call using 'nx::current object'
      [current object] print;
    }
    :show
  }

.CE
.SH COPYRIGHT
.nf
Copyright (c) 2014-19 Stefan Sobernig <stefan\&.sobernig@wu\&.ac\&.at>, Gustaf Neumann <gustaf\&.neumann@wu\&.ac\&.at>; available under the Creative Commons Attribution 3\&.0 Austria license (CC BY 3\&.0 AT)\&.

.fi