Tcl_AppInit(3) Tcl (7.0) Tcl_AppInit(3)
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NAME
Tcl_AppInit - perform application-specific initialization
SYNOPSIS
#include <tcl.h>
int
Tcl_AppInit(interp)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter for the
application.
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DESCRIPTION
Tcl_AppInit is a ``hook'' procedure that is invoked by the
main programs for Tcl applications such as tclsh and wish.
Its purpose is to allow new Tcl applications to be created
without modifying the main programs provided as part of Tcl
and Tk. To create a new application you write a new version
of Tcl_AppInit to replace the default version provided by
Tcl, then link your new Tcl_AppInit with the Tcl library.
Tcl_AppInit is invoked after by Tcl_Main and Tk_Main after
their own initialization and before entering the main loop
to process commands. Here are some examples of things that
Tcl_AppInit might do:
[1] Call initialization procedures for various packages
used by the application. Each initialization procedure
adds new commands to interp for its package and
performs other package-specific initialization.
[2] Process command-line arguments, which can be accessed
from the Tcl variables argv and argv0 in interp.
[3] Invoke a startup script to initialize the application.
Tcl_AppInit returns TCL_OK or TCL_ERROR. If it returns
TCL_ERROR then it must leave an error message in interp-
>result; otherwise the result is ignored.
In addition to Tcl_AppInit, your application should also
contain a procedure main that calls Tcl_Main as follows:
Tcl_Main(argc, argv, Tcl_AppInit);
The third argument to Tcl_Main gives the address of the
application-specific initialization procedure to invoke.
This means that you don't have to use the name Tcl_AppInit
for the procedure, but in practice the name is nearly always
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Tcl_AppInit(3) Tcl (7.0) Tcl_AppInit(3)
Tcl_AppInit (in versions before Tcl 7.4 the name Tcl_AppInit
was implicit; there was no way to specify the procedure
explicitly). The best way to get started is to make a copy
of the file tclAppInit.c from the Tcl library or source
directory. It already contains a main procedure and a
template for Tcl_AppInit that you can modify for your
application.
KEYWORDS
application, argument, command, initialization, interpreter
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