Re: [matplotlib-devel] repeated calls to show() are now OK?

[Michiel de H. <mjl...@ya...>]

So on Linux, show(block=True) blocks but show(block=False) doesn't? If matplotlib is in interactive mode, does show(block=True) still block? Because if matplotlib is in interactive mode, then the call to matplotlib.interactive(True) shouldn't make a difference, and I would expect show(block=True) and show(block=False) to behave the same way.

--Michiel.

--- On Sat, 6/12/10, Eric Firing <ef...@ha...> wrote:

> From: Eric Firing <ef...@ha...>
> Subject: Re: [matplotlib-devel] repeated calls to show() are now OK?
> To: "Michiel de Hoon" <mjl...@ya...>
> Cc: "John Hunter" <jd...@gm...>, "matplotlib development list" <mat...@li...>
> Date: Saturday, June 12, 2010, 11:32 PM
> On 06/12/2010 05:37 AM, Michiel de
> Hoon wrote:
> > --- On Sat, 6/12/10, Eric Firing<ef...@ha...> 
> 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.
> 
> 
>