'\"
'\" Generated from file 'critcl_iassoc\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2011-2018 Andreas Kupries
'\"
.TH "critcl::iassoc" n 1\&.1 doc "C Runtime In Tcl (CriTcl)"
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.BS
.SH NAME
critcl::iassoc \- CriTcl Utilities: Tcl Interp Associations
.SH SYNOPSIS
package require \fBTcl  8\&.4\fR
.sp
package require \fBcritcl  ?3\&.1?\fR
.sp
package require \fBcritcl::iassoc  ?1\&.1?\fR
.sp
\fB::critcl::iassoc::def\fR \fIname\fR \fIarguments\fR \fIstruct\fR \fIconstructor\fR \fIdestructor\fR
.sp
.BE
.SH DESCRIPTION
.PP
\fIC Runtime In Tcl\fR, or \fICriTcl\fR , is a system for compiling C code
embedded in Tcl on the fly and either loading the resulting objects into Tcl for
immediate use or packaging them for distribution\&.  Use \fICriTcl\fR to improve
performance by rewriting in C those routines that are performance bottlenecks\&.
.PP
This document is the reference manpage for the \fBcritcl::iassoc\fR
package\&. This package provides convenience commands for advanced
functionality built on top of the critcl core\&.
.PP
With it a user wishing to associate some data with a Tcl
interpreter via Tcl's \fBTcl_(Get|Set)AssocData()\fR APIs can now
concentrate on the data itself, while all the necessary boilerplate
around it is managed by this package\&.
.PP
Its intended audience are mainly developers wishing to write
Tcl packages with embedded C code\&.
.PP
This package resides in the Core Package Layer of CriTcl\&.
.PP
.PS
.nf
+----------------+
|Applications    |
| critcl         |
| critcl::app    |
+----------------+

*================*
|Core Packages   |
| critcl         |
| critcl::util   |
*================*

+----------------+
|Support Packages|
| stubs::*       |
| md5, platform  |
|  \&.\&.\&.           |
+----------------+

.fi
.PE
.PP
.SH API
.TP
\fB::critcl::iassoc::def\fR \fIname\fR \fIarguments\fR \fIstruct\fR \fIconstructor\fR \fIdestructor\fR
This command defines a C function with the given \fIname\fR which
provides access to a structure associated with a Tcl interpreter\&.
.sp
The C code code fragment \fIstruct\fR defines the elements of
said structure, whereas the fragments \fIconstructor\fR and
\fIdestructor\fR are C code blocks executed to initialize and release
any dynamically allocated parts of this structure, when needed\&. Note
that the structure itself is managed by the system\&.
.sp
The new function takes a \fBTcl_Interp*\fR pointer refering
to the interpreter whose structure we wish to obtain as the first
argument, plus the specified \fIarguments\fR and returns a pointer to
the associated structure, of type "\fIname\fR_data" (see below)\&.
.sp
The \fIarguments\fR are a dictionary-like list of C types and
identifiers specifying additional arguments for the accessor function,
and, indirectly, the \fIconstructor\fR C code block\&. This is useful
for the supplication of initialization values, or the return of more
complex error information in case of a construction failure\&.
.sp
The C types associated with the structure are derived from
\fIname\fR, with "\fIname\fR_data__" the type of the structure itself,
and "\fIname\fR_data" representing a pointer to the structure\&.
The C code blocks can rely on the following C environments:
.RS
.TP
\fIconstructor\fR
.RS
.TP
\fBdata\fR
Pointer to the structure (type: \fIname\fR_data) to
initialize\&.
.TP
\fBinterp\fR
Pointer to the Tcl interpreter (type: Tcl_Interp*)
the new structure will be associated with\&.
.TP
error
A C code label the constructor can jump to should it have
to signal a construction failure\&. It is the responsibility of the
constructor to release any fields already initialized before jumping
to this label\&.
.TP
\&.\&.\&.
The names of the constructor arguments specified with
\fIarguments\fR\&.
.RE
.TP
\fIdestructor\fR
.RS
.TP
\fBdata\fR
Pointer to the structure being released\&.
.TP
\fBinterp\fR
Pointer to the Tcl interpreter the structure
belonged to\&.
.RE
.RE
.PP
.SH EXAMPLE
The example shown below is the specification of a simple interpreter-associated
counter\&. The full example, with meta data and other incidentals, can be found
in the directory "\fIexamples/queue\fR" of the critcl source
distribution/repository\&.
.CS


package require Tcl 8\&.4
package require critcl 3\&.1

critcl::buildrequirement {
    package require critcl::iassoc
}

critcl::iassoc::def icounter {} {
    int counter; /* The counter variable */
} {
    data->counter = 0;
} {
    /* Nothing to release */
}

critcl::ccode {
    \&.\&.\&. function (\&.\&.\&.)
    {
         /* Access to the data \&.\&.\&. */
         icounter_data D = icounter (interp /* \&.\&.\&. any declared arguments, here, none */);
	 \&.\&.\&. D->counter \&.\&.\&.
    }
}
# or, of course, 'cproc's, 'ccommand's etc\&.

package provide icounter 1

.CE
.SH AUTHORS
Andreas Kupries
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such at \fIhttps://github\&.com/andreas-kupries/critcl\fR\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.SH KEYWORDS
C code, Embedded C Code, Tcl Interp Association, code generator, compile & run, compiler, dynamic code generation, dynamic compilation, generate package, linker, on demand compilation, on-the-fly compilation, singleton
.SH CATEGORY
Glueing/Embedded C code
.SH COPYRIGHT
.nf
Copyright (c) 2011-2018 Andreas Kupries

.fi
