Implementation of patch 869468

Allow the user to create Tkinter.Tcl objects which are
just like Tkinter.Tk objects except that they do not
initialize Tk. This is useful in circumstances where the
script is being run on machines that do not have an X
server running -- in those cases, Tk initialization fails,
even if no window is ever created.

Includes documentation change and tests.

Tested on Linux, Solaris and Windows.

Reviewed by Martin von Loewis.

Modules/_tkinter.c

@@ -546,15 +546,19 @@ int
 Tcl_AppInit(Tcl_Interp *interp)
 {
 	Tk_Window main;
+	const char * _tkinter_skip_tk_init;
 
-	main = Tk_MainWindow(interp);
 	if (Tcl_Init(interp) == TCL_ERROR) {
 		PySys_WriteStderr("Tcl_Init error: %s\n", Tcl_GetStringResult(interp));
 		return TCL_ERROR;
 	}
-	if (Tk_Init(interp) == TCL_ERROR) {
-		PySys_WriteStderr("Tk_Init error: %s\n", Tcl_GetStringResult(interp));
-		return TCL_ERROR;
+	_tkinter_skip_tk_init =	Tcl_GetVar(interp, "_tkinter_skip_tk_init", TCL_GLOBAL_ONLY);
+	if (_tkinter_skip_tk_init == NULL || strcmp(_tkinter_skip_tk_init, "1")	!= 0) {
+		main = Tk_MainWindow(interp);
+		if (Tk_Init(interp) == TCL_ERROR) {
+			PySys_WriteStderr("Tk_Init error: %s\n", Tcl_GetStringResult(interp));
+			return TCL_ERROR;
+		}
 	}
 	return TCL_OK;
 }
@@ -572,11 +576,10 @@ static void DisableEventHook(void); /* Forward */
 
 static TkappObject *
 Tkapp_New(char *screenName, char *baseName, char *className,
-	  int interactive, int wantobjects)
+	  int interactive, int wantobjects, int	wantTk)
 {
 	TkappObject *v;
 	char *argv0;
-
 	v = PyObject_New(TkappObject, &Tkapp_Type);
 	if (v == NULL)
 		return NULL;
@@ -637,6 +640,10 @@ Tkapp_New(char *screenName, char *baseName, char *className,
 	Tcl_SetVar(v->interp, "argv0", argv0, TCL_GLOBAL_ONLY);
 	ckfree(argv0);
 
+	if (! wantTk) {
+	    Tcl_SetVar(v->interp, "_tkinter_skip_tk_init", "1",	TCL_GLOBAL_ONLY);
+	}
+
 	if (Tcl_AppInit(v->interp) != TCL_OK)
 		return (TkappObject *)Tkinter_Error((PyObject *)v);
 
@@ -2562,6 +2569,41 @@ Tkapp_InterpAddr(PyObject *self, PyObject *args)
 	return PyInt_FromLong((long)Tkapp_Interp(self));
 }
 
+static PyObject	*
+Tkapp_TkInit(PyObject *self, PyObject *args)
+{
+	Tcl_Interp *interp = Tkapp_Interp(self);
+	Tk_Window main;
+	const char * _tk_exists = NULL;
+	PyObject *res =	NULL;
+	int err;
+	main = Tk_MainWindow(interp);
+	if (!PyArg_ParseTuple(args, ":loadtk"))
+		return NULL;
+
+	/* We want to guard against calling Tk_Init() multiple times */
+	CHECK_TCL_APPARTMENT;
+	ENTER_TCL
+	err = Tcl_Eval(Tkapp_Interp(self), "info exists	tk_version");
+	ENTER_OVERLAP
+	if (err == TCL_ERROR) {
+		res = Tkinter_Error(self);
+	} else {
+		_tk_exists = Tkapp_Result(self);
+	}
+	LEAVE_OVERLAP_TCL
+	if (err == TCL_ERROR) {
+		return NULL;
+	}
+	if (_tk_exists == NULL || strcmp(_tk_exists, "1") != 0)	{
+		if (Tk_Init(interp)	== TCL_ERROR) {
+		        PyErr_SetString(Tkinter_TclError, Tcl_GetStringResult(Tkapp_Interp(self)));
+			return NULL;
+		}
+	}
+	Py_INCREF(Py_None);
+	return Py_None;
+}
 
 static PyObject *
 Tkapp_WantObjects(PyObject *self, PyObject *args)
@@ -2629,6 +2671,7 @@ static PyMethodDef Tkapp_methods[] =
 	{"dooneevent", 	       Tkapp_DoOneEvent, METH_VARARGS},
 	{"quit", 	       Tkapp_Quit, METH_VARARGS},
 	{"interpaddr",         Tkapp_InterpAddr, METH_VARARGS},
+	{"loadtk",	       Tkapp_TkInit, METH_VARARGS},
 	{NULL, 		       NULL}
 };
 
@@ -2793,6 +2836,7 @@ Tkinter_Create(PyObject *self, PyObject *args)
 	char *className = NULL;
 	int interactive = 0;
 	int wantobjects = 0;
+	int wantTk = 1;	/* If false, then Tk_Init() doesn't get	called */
 
 	baseName = strrchr(Py_GetProgramName(), '/');
 	if (baseName != NULL)
@@ -2801,13 +2845,13 @@ Tkinter_Create(PyObject *self, PyObject *args)
 		baseName = Py_GetProgramName();
 	className = "Tk";
   
-	if (!PyArg_ParseTuple(args, "|zssii:create",
+	if (!PyArg_ParseTuple(args, "|zssiii:create",
 			      &screenName, &baseName, &className,
-			      &interactive, &wantobjects))
+			      &interactive, &wantobjects, &wantTk))
 		return NULL;
 
 	return (PyObject *) Tkapp_New(screenName, baseName, className, 
-				      interactive, wantobjects);
+				      interactive, wantobjects,	wantTk);
 }
 
 static PyObject *

Modules/tkappinit.c

@@ -19,6 +19,7 @@ int
 Tcl_AppInit(Tcl_Interp *interp)
 {
 	Tk_Window main_window;
+	const char * _tkinter_skip_tk_init;
 
 #ifdef TK_AQUA
 #ifndef MAX_PATH_LEN
@@ -68,7 +69,15 @@ Tcl_AppInit(Tcl_Interp *interp)
 	TclSetLibraryPath(pathPtr);
 #endif
 
-	if (Tk_Init (interp) == TCL_ERROR)
+#ifdef WITH_XXX
+		// Initialize modules that don't require Tk
+#endif
+
+	_tkinter_skip_tk_init =	Tcl_GetVar(interp, "_tkinter_skip_tk_init", TCL_GLOBAL_ONLY);
+	if (_tkinter_skip_tk_init != NULL && strcmp(_tkinter_skip_tk_init, "1")	== 0) {
+		return TCL_OK;
+	}
+	if (Tk_Init(interp) == TCL_ERROR)
 		return TCL_ERROR;
 
 	main_window = Tk_MainWindow(interp);