On 06/12/2010 05:37 AM, Michiel de Hoon wrote:
> --- On Sat, 6/12/10, Eric Firing<efir...@hawaii.edu> wrote:
>>> With TkAgg on Mac OS X, the first call to show()
>>> blocks, and returns when all figures are closed by the user.
>>> However, subsequent calls to show() return immediately.
>>
>> This is anomalous, then; on linux, no call to show blocks
>> with tkagg.
>> Puzzling difference.
>
> If I remove the _needmain stuff in the show() function in the TkAgg backend,
> then each call to show() blocks on Mac OS X with the TkAgg backend, which (in
> my understanding) is the desired behavior. I don't know the purpose of
> _needmain in the show() function, other than to disallow multiple calls to
> show().
>
> --Michiel.
>
I committed a change to backend_tkagg that leaves the show functionality
exactly as it is at present, but that facilitates testing of a simpler
version that I think is more consistent with the other backends and with
what we want. (I have appended the whole function to this message--see
below for additional explanation.)
I have also done some more exploration and testing, and here are my
tentative conclusions:
1) We should aim for a show() that blocks until all windows are closed,
on all backends, and in all environments. I think this is clearly
something that many users would like; it has reasonable use cases; and
it is simple, consistent, and easy to explain.
2) The big problem is the "in all environments" part of that statement.
We probably can't achieve the goal, but I suspect that over the long
term we can approach it, and the result will be "good enough".
3) As a step in that direction, I would like to see enough testing of Tk
with show(block=True) so that, if it works, we can transition towards
that behavior as the default, deprecate the old behavior, and eventually
eliminate it. Presently, TkAgg is most anomalous among the major backends.
4) Leaving the documentation (all in the FAQ) with its caution against
anything but a single show() at the end of a script is fine for 1.0;
supporting multiple calls to a blocking show under mildly restrictive
conditions is a reasonable goal for a subsequent release.
Eric
------------------------------------------------
def show(block=False):
"""
Show all figures.
Temporary, experimental kwarg *block* defaults to False to
provide the behavior present throughout mpl history to date:
interactive mode is forced on, and show does not block.
Set *block* to True to test the proposed new behavior,
consistent with other backends, in which show does not affect
interactive mode, and always blocks until all figures are closed.
In addition, the rcParam['tk.pythoninspect'] is ignored.
Use this kwarg only for testing; other backends do not accept
a kwarg to show, and might never do so.
"""
for manager in Gcf.get_all_fig_managers():
manager.show()
if block:
# proposed new behavior; seems to make this backend consistent
# with others, with no drawbacks identified yet.
Tk.mainloop()
else:
# long-time behavior: non-blocking, forces interactive mode
import matplotlib
matplotlib.interactive(True)
if rcParams['tk.pythoninspect']:
os.environ['PYTHONINSPECT'] = '1'
if show._needmain:
Tk.mainloop()
show._needmain = False
show._needmain = True # This can go away if we eliminate block=False
option.
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