Tcl_AppInit(3) Tcl Library Procedures 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 enter-ing entering
ing 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 initializa-tion initialization
tion 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 for the interpreter's 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 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
Tcl 7.0 Tcl_AppInit(3)
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