Hi Joe,
Thanks for bringing this up, it is certainly valuable to highlight this on
the mailinglist. As you say, the change is hard to spot and, I agree, makes
library code supporting v1.1.1 and v1.2 harder than one would like.
Typically, anything which is going to break core APIs (even slightly)
should be documented under the "API Changes" page here
http://matplotlib.org/api/api_changes.html#changes-in-1-2-x . You will find
there were quite a few changes made relating to transforms which I think is
entirely my doing, so at least we know who the guilty party is :-)
Thanks for spotting the example failure - I split these changes over many
separate pull requests and did scan the gallery for any noticeable changes,
but this one must have slipped the net.
If you're still having problems with using the newer transform API, please
shout and I'd be happy to have a look for you.
All the best,
Phil
On 9 December 2012 22:10, Joe Kington <joferking...@gmail.com> wrote:
> Hi folks,
>
> At some point transforms.Transform was slightly refactored.
> (Particularly, this commit:
> https://github.com/matplotlib/matplotlib/commit/8bbe2e55f29b28ba558504b27596b8e36a087c1c)
> This changed what methods need to be overridden when subclassing
> Transform.
>
> All in all, it seems like a very sensible change, but it led to some very
> hard-to-find bugs in some of my code that subclasses transforms.Transform.
> I thought I would mention it on the mailing list for anyone else that uses
> custom projections. Forgive me if it was mentioned earlier and I just
> didn't notice.
>
> With versions 1.1.x and older, one had to directly implement a
> transformmethod when subclassingtransforms.Transform,
> otherwise a NotImplemented error would be raised.
>
> With versions 1.2.x and newer, the preferred way appears to be to
> implement things in a separate transform_affine or transform_non_affinemethod
> and not explicitly implement a
> transform method.
>
> If you implement the non-affine portion directly in the transform method
> without overriding transform_non_affine, it leads to strange drawing bugs
> with v1.2 that did not occur with older versions. (For example, this broke
> one of the examples in the gallery between 1.1. and 1.2:
> http://matplotlib.org/1.1.1/examples/api/custom_projection_example.html
> http://matplotlib.org/1.2.0/examples/api/custom_projection_example.html .
> I just submitted a pull request to update the example, by the way.)
>
> On the other hand, for compatibility with versions 1.1 and older, you have
> to explicitly implement the transform method as well, otherwise you'll
> get the NotImplemented error.
>
> Therefore, now one needs to explicitly implement *_both_* the
> transform_non_affine and transform methods of a custom non-affine
> transform for compatibility with 1.1 and older as well as 1.2 and newer.
>
> Similarly, one needs to implement* _both_ *the transform_path_non_affineand
> the
> transform_path methods for compatibility with newer and older versions of
> matplotlib.
>
> Arguably, it should have always been done this way, but based
> onexamples/api/custom_projection_example.py,
> I (and I suspect many other people as well) implemented the transform
> directly as the transform method when subclassing Transform, instead of
> separately in a transform_affine or transform_non_affine method.
>
> Is this a large enough change to warrant a mention in the changelog? (On
> the other hand, the mailing list probably gets a lot more eyes on it than
> the changelog...)
>
> Thanks!
> -Joe
>
>
>
> ------------------------------------------------------------------------------
> LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial
> Remotely access PCs and mobile devices and provide instant support
> Improve your efficiency, and focus on delivering more value-add services
> Discover what IT Professionals Know. Rescue delivers
> http://p.sf.net/sfu/logmein_12329d2d
> _______________________________________________
> Matplotlib-users mailing list
> Matplotlib-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>
------------------------------------------------------------------------------
LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial
Remotely access PCs and mobile devices and provide instant support
Improve your efficiency, and focus on delivering more value-add services
Discover what IT Professionals Know. Rescue delivers
http://p.sf.net/sfu/logmein_12329d2d
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
