Re: [matplotlib-devel] adding valid signals to a CallbackRegistry?

On Thu, Jun 23, 2011 at 6:55 PM, Benjamin Root <ben...@ou...> wrote:

> On Thu, Jun 23, 2011 at 4:29 PM, Eric Firing <ef...@ha...> wrote:
>
>> On 06/23/2011 10:53 AM, John Hunter wrote:
>> > On Thu, Jun 23, 2011 at 3:11 PM, Michael Droettboom<md...@st...>
>>  wrote:
>> >> On 06/23/2011 03:49 PM, Benjamin Root wrote:
>> >>
>> >> Hello all,
>> >>
>> >> I am working to make mplot3d feature-parity with regular axes objects.
>>  I
>> >> have come across a possible design flaw with the CallbackRegistry.
>> >>
>> >> Many of the Axes3D methods are merely wrappers around Axes methods
>> letting
>> >> it do the work for x and y axis and then let Axes3D do the same for the
>> z
>> >> axis.  In Axes.cla(), self.callbacks gets a CallbackRegistry of signals
>> >> named "xlim_changed" and "ylim_changed".  However, once that is set, it
>> does
>> >> not appear to be a way for me to add another signal of "zlim_changed"
>> in
>> >> Axes3D.cla().  I could replace self.callbacks with a new
>> CallbackRegistry,
>> >> but since there is a lot of interveaning code between that first
>> >> initialization of self.callbacks and coming back out of Axes.cla(), I
>> worry
>> >> that some callbacks may have been registered by then and would get
>> >> eliminated in the process.
>> >>
>> >> Is there a recommended way around this?  Or maybe this is more evidence
>> that
>> >> we should move towards the use of a dictionary of axis objects and make
>> Axes
>> >> functions more agnostic to the number of axis?
>> >>
>> >> I don't know if there is a way around it as the code currently stands.
>>  Your
>> >> proposal here:
>> >>
>> >> https://github.com/matplotlib/matplotlib/issues/379
>> >>
>> >> seems like one way out.  Then the code that creates the
>> CallbackRegistry in
>> >> Axes.cla() could iterate through all the axes and create a callback
>> type for
>> >> each of them.
>> >>
>> >> However, to step back from this, I've never quite understood why it was
>> >> necessary to have a fixed set of callback types in the CallbackRegistry
>> to
>> >> begin with.  It seems to me it comes from a history of callback
>> registry
>> >> classes I've seen in more static languages (such as libsigc++).  We
>> could
>> >> just as easily create new signal types on the fly as they are
>> registered.
>> >> You lose some error checking, I suppose, if the caller and receiver
>> don't
>> >> agree on the names, but seems like a small price to pay.
>> >
>> > CallbackRegistry.signals is a "public" attribute, so is there anything
>> > preventing you Ben from just doing
>> >
>> >    self.callbacks.signals.add('zlim_changed')
>> >
>> > and then connecting your desired callback?
>>
>> Yes, it requires some modification to the CallbackRegistry:
>>
>>     def __init__(self, signals):
>>         '*signals* is a sequence of valid signals'
>>         self.signals = set(signals)
>>         self.callbacks = dict([(s, dict()) for s in signals])
>>         self._cid = 0
>>
>> So adding to the set of signals is not enough.  It would be easy to made
>> an add_signal() method to take care of the two necessary steps.  It
>> would seem simpler, however, to just let the signals be added
>> automatically as needed, as I believe Mike is suggesting.
>>
>> Actually, it looks like self.signals could be replaced by a property
>> that, upon reading, would return self.callbacks.keys().  Why use two
>> data structures if one will do?  Of course, since signals is public,
>> that would represent API breakage--but of a rather obscure sort.
>>
>> (Shooting from the hip; I haven't looked closely.)
>>
>> Eric
>>
>>
> I am willing to go with whatever makes everyone happy.  I have a limited
> amount of time, and my goal with the feature-parity branch (found here:
> https://github.com/WeatherGod/matplotlib/tree/mplot3d/consistency ) is to
> get a z-version of every single axis-related function into Axes3D, and make
> sure that most other functions that operate on arbitrary axis are capable of
> acting on the z-axis.
>
> However, I do not intend to make sure that everything works (only that
> there are no regressions).  For example, setting axis label properties
> ('right', 'left', etc.) make little sense in the current context, and
> working with minor ticks do nothing in mplot3d.  The idea is that if the
> added functions work, then that is good news.  If the added functions do not
> work, then that can be a bug report.
>
> Therefore, anything that gets me to that goal would be fine.  Heck, doing
> nothing about this might also work because there never was a callback for
> zlim_changed before, so not having it now will be no loss of function.
>
> Sorry for rambling,
> Ben Root
>
>

I put up a pull request for adding the method "add_signal" to the
CallbackRegistry here: https://github.com/matplotlib/matplotlib/pull/381

Ben Root