doc/Tk_Main.3


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'\"
'\" Copyright (c) 1994 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: Tk_Main.3,v 1.4 2007/10/26 20:13:23 dgp Exp $
'\" 
.so man.macros
.TH Tk_Main 3 4.0 Tk "Tk Library Procedures"
.BS
.SH NAME
Tk_Main \- main program for Tk-based applications
.SH SYNOPSIS
.nf
\fB#include <tk.h>\fR
.sp
\fBTk_Main\fR(\fIargc, argv, appInitProc\fR)
.SH ARGUMENTS
.AS Tcl_AppInitProc *appInitProc
.AP int argc in
Number of elements in \fIargv\fR.
.AP char *argv[] in
Array of strings containing command-line arguments.
.AP Tcl_AppInitProc *appInitProc in
Address of an application-specific initialization procedure.
The value for this argument is usually \fBTcl_AppInit\fR.
.BE

.SH DESCRIPTION
.PP
\fBTk_Main\fR acts as the main program for most Tk-based applications.
Starting with Tk 4.0 it is not called \fBmain\fR anymore because it 
is part of the Tk library and having a function \fBmain\fR
in a library (particularly a shared library) causes problems on many
systems.
Having \fBmain\fR in the Tk library would also make it hard to use
Tk in C++ programs, since C++ programs must have special C++
\fBmain\fR functions.
.PP
Normally each application contains a small \fBmain\fR function that does
nothing but invoke \fBTk_Main\fR.
\fBTk_Main\fR then does all the work of creating and running a
\fBwish\fR-like application.
.PP
When it is has finished its own initialization, but before
it processes commands, \fBTk_Main\fR calls the procedure given by
the \fIappInitProc\fR argument.  This procedure provides a ``hook''
for the application to perform its own initialization, such as defining
application-specific commands.  The procedure must have an interface
that matches the type \fBTcl_AppInitProc\fR:
.CS
typedef int Tcl_AppInitProc(Tcl_Interp *\fIinterp\fR);
.CE
\fIAppInitProc\fR is almost always a pointer to \fBTcl_AppInit\fR;
for more details on this procedure, see the documentation
for \fBTcl_AppInit\fR.

.SH KEYWORDS
application-specific initialization, command-line arguments, main program