[matplotlib-devel] refactoring of show

[Eric F. <ef...@ha...>]

All,

John noticed that my changes to show() prior to 1.0 had broken a use 
case with tkagg and ipython -pylab, so I fixed that yesterday in 
maintenance branch and trunk.  Today, in 8562 and 8563, I did some 
refactoring to try to make show() behavior more understandable across 
backends, and easier to modify if necessary.  Specifically, we need to 
work with the ipython people to make sure the ipython 0.11 refactoring 
of interactive support works as intended.  I haven't done any testing 
with the development version of 0.11 yet.

At present, all interactive backends start a blocking mainloop only if 
ipython has not attached a _needmain flag to show(), and if mpl is not 
in interactive mode.

Under all script and ipython conditions, multiple calls to show in a 
session or script are permitted.

All interactive backends behave the same when run with ipython -pylab, 
version 0.10: show is non-blocking, regardless of whether it is executed 
on the command line (completely unnecessary) or is found in a script.

Under raw ipython (no -pylab or other threading flags provided), with 
mpl in non-interactive mode, all backends behave the same: show() is 
needed and blocks, but may be called multiple times.  With mpl in 
interactive mode, there are two categories: tkagg, fltkagg, gtk*, and 
qt4agg behave the same as in -pylab mode, so there so no longer any real 
need for the special threading modes; but wx* and qtagg do not behave in 
a useful way, so they still need the special threading.

All of the above is based on quick tests with my own system, ubuntu 
10.04.  I expect it will be the same for other supported systems, with 
the exception that behavior in raw ipython mode, with mpl in interactive 
mode, may not work with some earlier versions of gui toolkits--but I 
suspect we will not actually encounter this for supported versions.

I have not built or tested anything under Windows or OS X.  For the 
latter, testing of the macosx backend is needed.  I expect cocoaagg to 
behave differently than the others, but no differently than it did 
before my changes.

Eric