trick used for itcl-ng +widget

I have found a solution to my problems of defering to load Tk until it is needed in itcl-ng.

What I have done is:

in itcl-ng I have defined on C-level tcl commands for example:

Tcl_CreateObjCommand(interp, "::itcl::widget", Itcl_WidgetCmdStart,
    (ClientData)infoPtr, (Tcl_CmdDeleteProc*)NULL);

/*
 * ------------------------------------------------------------------------
 *  Itcl_WidgetCmdStart()
 *
 *  that is just a dummy command to load package ItclWidget
 *  and then to resend the command and execute it in that package
 *  package ItclWidget is renaming the Tcl command!!
 *
 * ------------------------------------------------------------------------
 */
int
Itcl_WidgetCmdStart(
    ClientData clientData,   /* info for all known objects */
    Tcl_Interp *interp,      /* current interpreter */
    int objc,                /* number of arguments */
    Tcl_Obj *CONST objv[])   /* argument objects */
{
    ItclShowArgs(0, "Itcl_WidgetCmdStart", objc, objv);
    const char *res = Tcl_PkgRequire(interp, "ItclWidget", "4.0", 0);
    if (res == NULL) {
        return TCL_ERROR;
    }
    return Tcl_EvalObjv(interp, objc, objv, 0);
}

and in the additional package ItclWidget, which is linked agaist Tk lib, I have the following:

TclRenameCommand(interp, "::itcl::widget", "::itcl::__widget");

Tcl_CreateObjCommand(interp, "::itcl::widget", Itcl_WidgetCmd,
    (ClientData)infoPtr, (Tcl_CmdDeleteProc*)NULL);


C-function Itcl_WidgetCmd is doing the real work from that point on, and as the Tcl_EvalObjv command is calling the parser again, now the Itcl_WidgetCmd is called without interaction from the user