[Python-Dev] PEP needed? Introducing Tcl objects

Jeff Hobbs JeffH@ActiveState.com
Wed, 20 Feb 2002 10:33:25 -0800

> So if TCL_DONT_WAIT isn't set, it will block; if it is, it will
> busy-wait. Looks like we lose either way.
> In-between, it invokes the setupProcs of each input source, so that
> they can set a maxblocktime, but I don't think _tkinter should hack
> itself into that process.

That's correct - I should have looked a bit more into what I did
before (I was always tying in another GUI's event loop).  However,
I don't see why you should not consider the extra event source.
Tk uses this itself for X.  It would be something like:

[in tk setup]
    Tcl_CreateEventSource(TkinterSetupProc, NULL, NULL);

 * TkinterSetupProc --
 *	This procedure implements the setup part of the Tkinter
 *	event source.  It is invoked by Tcl_DoOneEvent before entering
 *	the notifier to check for events on all displays.
 * Results:
 *	None.
 * Side effects:
 *	The maximum block time will be set to 20000 usecs to ensure that
 *	the notifier returns control to Tcl.

static void
TkinterSetupProc(clientData, flags)
    ClientData clientData;	/* Not used. */
    int flags;
    static Tcl_Time blockTime = { 0, 20000 };

In fact, you can look at tk/unix/tkUnixEvent.c to see something
similar already done in Tk.

> About thread-safety: Is Tcl 8.3 thread-safe in its standard
> installation, so that we can just use it from multiple threads? If
> not, what is the compile-time check to determine whether it is
> thread-safe? If there is none, I really don't see a solution, and the

You would compile with --enable-threads (both Tcl and Tk).