PythonCmd_Error() but failed to return. The error wasn't very likely
(only when we run out of memory) but since the check is there we might
as well return the error. (I think that Barry introduced this buglet
when he added error checks everywhere.)
# from my PC at home, but it can't send email :-(
Add a clarifying comment about the new ENTER_OVERLAP and
LEAVE_OVERLAP_TCL macros; get rid of all the bogus tests for deleted
interpreters (Tcl already tests for this; they were left over from an
earlier misguided attempt to fix the threading).
There were some serious problem with the thread-safety code.
The basic problem was that often the result was gotten out of
the Tcl interpreter object after releasing the Tcl lock.
Of course, another thread might have changed the return value
already, and this was indeed happening. (Amazing what trying
it on a different thread implementation does!)
The solution is to grab the Python lock without releasing the
Tcl lock, so it's safe to create a string object or set the
exceptions from the Tcl interpreter. Once that's done, the
Tcl lock is released.
Note that it's now legal to acquire the Python lock while the
the Tcl lock is held; but the reverse is not true: the Python
lock must be released before the Tcl lock is acquired. This
in order to avoid deadlines. Fortunately, there don't seem to
be any problems with this.
(The "sort of" is because it uses kbhit() to detect that the user
starts typing, and then no events are processed until they hit
return.)
Also fixed a nasty locking bug: EventHook() is called without the Tcl
lock set, so it can't use the ENTER_PYTHON and LEAVE_PYTHON macros,
which manipulate both the Python and the Tcl lock. I now only acquire
and release the Python lock.
(Haven't tested this on Unix yet...)
Tkinter. This adds a separate lock -- read the comments. (This was
also needed for Mark Hammond's attempts to make PythonWin
Tkinter-friendly.)
The changes have affected the EventHook slightly, too; and I've done
some more cleanup of the code that deals with the different versions
of Tcl_CreateFileHandler().
