'\"
'\" Generated from file 'lazyset\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2018 Roy Keene
'\"
.TH "lazyset" n 1 tcllib "Lazy evaluation for variables and arrays"
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.SH NAME
lazyset \- Lazy evaluation
.SH SYNOPSIS
package require \fBTcl  8\&.5\fR
.sp
package require \fBlazyset  ?1?\fR
.sp
\fB::lazyset::variable\fR ?\fI-array boolean\fR? ?\fI-appendArgs boolean\fR? \fIvariableName\fR \fIcommandPrefix\fR
.sp
.BE
.SH DESCRIPTION
.PP
The \fBlazyset\fR package provides a mechanism for deferring execution
of code until a specific variable or any index of an array is referenced\&.
.SH COMMANDS
.TP
\fB::lazyset::variable\fR ?\fI-array boolean\fR? ?\fI-appendArgs boolean\fR? \fIvariableName\fR \fIcommandPrefix\fR
Arrange for the code specified as \fIcommandPrefix\fR to be executed when
the variable whose name is specified by \fIvariableName\fR is read for
the first time\&.
If the optional argument \fI-array boolean\fR is specified as true,
then the variable specified as \fIvariableName\fR is treated as an
array and attempting to read any index of the array causes that
index to be set by the \fIcommandPrefix\fR as they are read\&.
If the optional argument \fI-appendArgs boolean\fR is specified as
false, then the variable name and subnames are not appended to the
\fIcommandPrefix\fR before it is evaluated\&.  If the argument
\fI-appendArgs boolean\fR is not specified or is specified as true
then 1 or 2 additional arguments are appended to the \fIcommandPrefix\fR\&.
If \fI-array boolean\fR is specified as true, then 2 arguments are
appended corresponding to the name of the variable and the index,
otherwise 1 argument is appended containing the name of variable\&.
The \fIcommandPrefix\fR code is run in the same scope as the variable
is read\&.
.PP
.SH EXAMPLES
.CS


	::lazyset::variable page {apply {{name} {
		package require http
		set token [http::geturl http://www\&.tcl\&.tk/]
		set data [http::data $token]
		return $data
	}}}

	puts $page

.CE
.CS


	::lazyset::variable -array true page {apply {{name index} {
		package require http
		set token [http::geturl $index]
		set data [http::data $token]
		return $data
	}}}

	puts $page(http://www\&.tcl\&.tk/)

.CE
.CS


	::lazyset::variable -appendArgs false simple {
		return -level 0 42
	}

	puts $simple

.CE
.SH AUTHORS
Roy Keene
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIutility\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH CATEGORY
Utility
.SH COPYRIGHT
.nf
Copyright (c) 2018 Roy Keene

.fi