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Tcl_AppInit(3)		    Tcl	Library	Procedures		Tcl_AppInit(3)


       Tcl_AppInit - perform application-specific initialization

       #include	<tcl.h>


       Tcl_Interp *interp (in)		Interpreter for	the application.

       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 by Tcl_Main and Tk_Main after their own initial-
       ization	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  ini-

       [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.

       [4]    Use the routines Tcl_SetStartupScript  and  Tcl_GetStartupScript
	      to  set  or query	the file and encoding that the active Tcl_Main
	      or Tk_Main routine will use as a startup script.

       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;	other-
       wise the	result is ignored.

       In addition to Tcl_AppInit, your	application should also	contain	a pro-
       cedure 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  do
       not 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	proce-
       dure 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.


       application, argument, command, initialization, interpreter

Tcl				      7.0			Tcl_AppInit(3)


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