Re: [Matplotlib-users] Avoid circular references with format_coord and Qt?

[Thomas C. <tca...@gm...>]

My knee-jerk reaction is to move the definition of `format` outside of the
`Visualize.__init__` method.  If you need to have hooks back into the
visualize method I would use a function factory + weak refs or a class
(again with weakrefs) with a `__call__` method.

Tom

On Sun, Mar 8, 2015 at 3:35 PM Sebastian Berg <seb...@si...>
wrote:

> Hey,
>
> probably there is nothing to help me here, but I have a QtGui, using
> matplotlib and basically end up in a circular reference hell that is not
> resolvable by the gc. After removing almost all circular references, the
> python inherited QWidget that embeds the figurecanvas is now deleted
> fine.
>
> The thing I end up with however is something like
>
> class Visualize(object):
>      def __init__(self):
>          self.figure = Figure()
>          canvas = FigureCanvas(self.figure)
>          PythonInheritedQtWidget(self).element.setWidget(canvas)
>
>          def format(*args):
>              # do stuff
>              return something
>          self.axis = self.figure.add_subplot(1, 1, 1)
>          self.axis.format_coord = format
>
>          # This was completely drawn with canvas and all
>          # PythonInheritedQtWidget is deleted fine.
>
> I have not been able to get a minimal test case. But I have it pinned
> down that everything can get cleaned up after:
>
> del Visualize.axes.format_coord
>
> so the circular reference that makes it not collectable is only the
> format_coord which is a method pointing to the class owning the figure
> and the axis. I am about to just use a weak reference wrapper function
> to break the circle but it seems silly.
>
> Anyway, I do not expect that anyone can help, and I expect it is some Qt
> stuff really, but this is seriously annoying me....
>
> - Sebastian
> ------------------------------------------------------------
> ------------------
> Dive into the World of Parallel Programming The Go Parallel Website,
> sponsored
> by Intel and developed in partnership with Slashdot Media, is your hub for
> all
> things parallel software development, from weekly thought leadership blogs
> to
> news, videos, case studies, tutorials and more. Take a look and join the
> conversation now. http://goparallel.sourceforge.net/
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>