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[comment {-*- tcl -*- doctools manpage}]
[vset bitmap_version 1.1]
[manpage_begin critcl::bitmap 3tcl [vset bitmap_version]]
[include include/module2.inc]
[keywords singleton {Tcl Interp Association}]
[keywords bitmask bitset flags]
[titledesc {CriTcl - Wrap Support - Bitset en- and decoding}]
[require Tcl 8.6]
[require critcl [opt 3.2]]
[require critcl::bitmap [opt [vset bitmap_version]]]
[description]
[para]
[include include/welcome.inc]
[para]
This document is the reference manpage for the
[package critcl::bitmap] package. This package provides convenience
commands for advanced functionality built on top of both critcl core
and package [package critcl::iassoc].
[para] C level libraries often use bit-sets to encode many flags into a
single value. Tcl bindings to such libraries now have the task of
converting a Tcl representation of such flags (like a list of strings)
into such bit-sets, and back.
[emph Note] here that the C-level information has to be something which
already exists. The package does [emph not] create these values. This is
in contrast to the package [package critcl::enum] which creates an
enumeration based on the specified symbolic names.
[para] This package was written to make the declaration and management
of such bit-sets and their associated conversions functions easy,
hiding all attendant complexity from the user.
[para] Its intended audience are mainly developers wishing to write
Tcl packages with embedded C code.
[para] This package resides in the Core Package Layer of CriTcl.
[para][image arch_core][para]
[comment {= = == === ===== ======== ============= =====================}]
[section API]
[list_begin definitions]
[call [cmd ::critcl::bitmap::def] [arg name] [arg definition] [opt [arg exclusions]]]
This command defines two C functions for the conversion of the
[arg name]d bit-set into Tcl lists, and vice versa.
The underlying mapping tables are automatically initialized on first
access, and finalized on interpreter destruction.
[para] The [arg definition] dictionary provides the mapping from the
Tcl-level symbolic names of the flags to their C expressions (often
the name of the macro specifying the actual value).
[emph Note] here that the C-level information has to be something which
already exists. The package does [emph not] create these values. This is
in contrast to the package [package critcl::enum] which creates an
enumeration based on the specified symbolic names.
[para] The optional [arg exlusion] list is for the flags/bit-sets for
which conversion from bit-set to flag, i.e. decoding makes no
sense. One case for such, for example, are flags representing a
combination of other flags.
[para] The package generates multiple things (declarations and
definitions) with names derived from [arg name], which has to be a
proper C identifier.
[list_begin definitions]
[def [arg name]_encode]
The function for encoding a Tcl list of strings into the equivalent
bit-set.
Its signature is
[para][example_begin]
int [arg name]_encode (Tcl_Interp* interp, Tcl_Obj* flags, int* result);
[example_end]
[para] The return value of the function is a Tcl error code,
i.e. [const TCL_OK], [const TCL_ERROR], etc.
[def [arg name]_decode]
The function for decoding a bit-set into the equivalent Tcl list of
strings.
Its signature is
[para][example_begin]
Tcl_Obj* [arg name]_decode (Tcl_Interp* interp, int flags);
[example_end]
[def [arg name].h]
A header file containing the declarations for the two conversion
functions, for use by other parts of the system, if necessary.
[para] The generated file is stored in a place where it will not
interfere with the overall system outside of the package, yet also be
available for easy inclusion by package files ([cmd csources]).
[def [arg name]]
The name of a critcl argument type encapsulating the encoder function
for use by [cmd critcl::cproc].
[def [arg name]]
The name of a critcl result type encapsulating the decoder function
for use by [cmd critcl::cproc].
[list_end]
[list_end]
[comment {= = == === ===== ======== ============= =====================}]
[section Example]
The example shown below is the specification of the event flags pulled
from the draft work on a Tcl binding to Linux's inotify APIs.
[example {
package require Tcl 8.6
package require critcl 3.2
critcl::buildrequirement {
package require critcl::bitmap
}
critcl::bitmap::def tcl_inotify_events {
accessed IN_ACCESS
all IN_ALL_EVENTS
attribute IN_ATTRIB
closed IN_CLOSE
closed-nowrite IN_CLOSE_NOWRITE
closed-write IN_CLOSE_WRITE
created IN_CREATE
deleted IN_DELETE
deleted-self IN_DELETE_SELF
dir-only IN_ONLYDIR
dont-follow IN_DONT_FOLLOW
modified IN_MODIFY
move IN_MOVE
moved-from IN_MOVED_FROM
moved-self IN_MOVE_SELF
moved-to IN_MOVED_TO
oneshot IN_ONESHOT
open IN_OPEN
overflow IN_Q_OVERFLOW
unmount IN_UNMOUNT
} {
all closed move oneshot
}
# Declarations: tcl_inotify_events.h
# Encoder: int tcl_inotify_events_encode (Tcl_Interp* interp, Tcl_Obj* flags, int* result);
# Decoder: Tcl_Obj* tcl_inotify_events_decode (Tcl_Interp* interp, int flags);
# crit arg-type tcl_inotify_events
# crit res-type tcl_inotify_events
}]
[comment {= = == === ===== ======== ============= =====================}]
[include include/feedback2.inc]
[manpage_end]
|
