On Thu, Feb 7, 2013 at 8:40 PM, Antony Lee <antony....@berkeley.edu> wrote: > Hi, > > I saw that a discussion started on transitioning to the use of properties > instead of explicit getters and setters, which seems like a very good idea > to me... so I thought this would be a good idea to get involved in > matplotlib-devel :) > > Right now an issue raised is what to do with set_* that take multiple > arguments. Taking set_title, which takes both positional and keyword > arguments, as an example, my idea would be to do > > ax.title = "A title" > ax.title.fontdict = fontdict > > Basically, a property "foo" (in the matplotlib meaning of the word) becomes > a descriptor with __get__ => get_foo and __set__ => set_foo, and keyword > arguments to the old property setter become themselves descriptors on that > descriptor.
Unfortunately descriptors don't really work like that, because when you do `.title` on an instance that doesn't return the descriptor itself, it just returns the result of `__get__` on the descriptor. So in your example `.fontdict` would have to be an attribute on any string assigned as the title. So what you really have to do for this to work is to wrap every value returned by the descriptor in some kind of proxy that adds the appropriate extra attributes. It also has to do so in a way that the proxy can behave transparently like the wrapped object, and that none of the wrapped objects attributes are overshadowed. And it has to hypothetically work with instances any any arbitrary type or class. While this is somewhat doable for a limited set cases it's really more of a can of worms than it's worth. Believe me, I've tried to solve similar problems to this one before. A couple easier solutions: Allow the `.title` (and other such attributes) to be assigned to with a (value, options) tuple where the value is the title itself, and the options is a dictionary or tuple of supported options for the title. Another solution is to just keep set_title() for cases like this if one wishes to set the title with additional options (while still allowing `.title = 'foo'` for the simple case). ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
