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Tcl_AppInit (3)

perform application-specific initialization

SYNOPSIS

    #include <tcl.h>
    int
    Tcl_AppInit(interp)
    

ARGUMENTS

    Tcl_Interp *interp Tcl_Interp *interp in Interpreter for the application.

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:

      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.

      Process command-line arguments, which can be accessed from the Tcl variables argv and argv0 in interp.

      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 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 '\" '\" Copyright (c) 1989-1993 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: Async.3,v 1.2 1998/09/14 18:39:46 stanton Exp $ '\" '\" The definitions below are for supplemental macros used in Tcl/Tk '\" manual entries. '\" '\" .AP type name in/out ?indent? '\" Start paragraph describing an argument to a library procedure. '\" type is type of argument (int, etc.), in/out is either "in", "out", '\" or "in/out" to describe whether procedure reads or modifies arg, '\" and indent is equivalent to second arg of .IP (shouldn't ever be '\" needed; use .AS below instead) '\" '\" .AS ?type? ?name? '\" Give maximum sizes of arguments for setting tab stops. Type and '\" name are examples of largest possible arguments that will be passed '\" to .AP later. If args are omitted, default tab stops are used. '\" '\" .BS '\" Start box enclosure. From here until next .BE, everything will be '\" enclosed in one large box. '\" '\" .BE '\" End of box enclosure. '\" '\" .CS '\" Begin code excerpt. '\" '\" .CE '\" End code excerpt. '\" '\" .VS ?version? ?br? '\" Begin vertical sidebar, for use in marking newly-changed parts '\" of man pages. The first argument is ignored and used for recording '\" the version when the .VS was added, so that the sidebars can be '\" found and removed when they reach a certain age. If another argument '\" is present, then a line break is forced before starting the sidebar. '\" '\" .VE '\" End of vertical sidebar. '\" '\" .DS '\" Begin an indented unfilled display. '\" '\" .DE '\" End of indented unfilled display. '\" '\" .SO '\" Start of list of standard options for a Tk widget. The '\" options follow on successive lines, in four columns separated '\" by tabs. '\" '\" .SE '\" End of list of standard options for a Tk widget. '\" '\" .OP cmdName dbName dbClass '\" Start of description of a specific option. cmdName gives the '\" option's name as specified in the class command, dbName gives '\" the option's name in the option database, and dbClass gives '\" the option's class in the option database. '\" '\" .UL arg1 arg2 '\" Print arg1 underlined, then print arg2 normally. '\" '\" RCS: @(#) $Id: man.macros,v 1.2 1998/09/14 18:39:54 stanton Exp $ '\" '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. t .wh -1.3i ^B ^l \n(.l b '\" # Start an argument description AP !"\\$4"" .TP \\$4 \{\ !"\\$2"" .TP \\n()Cu .TP 15