AppInit

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 pro-
       grams 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  ini-
              tialization.

       [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;  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 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 con-
       tains a main procedure and a template for Tcl_AppInit that you can mod-
       ify for your application.


KEYWORDS
       application, argument, command, initialization, interpreter



Tcl                                   7.0                       Tcl_AppInit(3)