Re: [matplotlib-devel] Several patches: kwargs cleanup, legend-kwargs, legend-fontsize

[John H. <jdh...@ac...>]

>>>>> "Norbert" == Norbert Nemec <Nor...@gm...> writes:

    Norbert> Ouch, sorry, I do not even have 2.2 installed. Guess with
    Norbert> that information, the whole patch becomes bogus.

    Norbert> On the other hand: simpy reverting pop to get leaves you
    Norbert> with the old problem: you have to drop the check for
    Norbert> emptyness of kwargs since legal arguments are not removed
    Norbert> after use. If, on the other hand, you remove this check,
    Norbert> erraneous (p.e. misspelled) arguments are just silently
    Norbert> ignored.

    Norbert> Maybe, a wrapper would solve the problem? How would one
    Norbert> code a replacement for pop that works on 2.2 as well?
    Norbert> Probably easiest by using get and del within a
    Norbert> try..except block? The wrapper could then have a clear
    Norbert> note how to replace it once 2.3 becomes mandatory
    Norbert> sometimes in the future.

I added a method popd to matplotlib.cbook.  It should work just like
d.pop(key) but you call popd(d, key).  Like pop, it accepts a default
value.

Before we reapply your patch to raise on bad kwargs, I think it's
worth getting some input if we want to raise on nonexistent keys.  In
some cases, it might be desirable to be able to do, for example

  legend(handles, labels, linewidth=2, fontsize=12)

From an implementation standpoint, it's easiest to implement something
like this using anonymous **kwargs, and iterate over all the handles
and text objects calling set_someprop(val) if set_someprop exists for
some object.

Ie, rather than making all the keyword args explicit and therefore
having to add explicitly add all the setters for line, text and patch
to the kwargs of Legend, which would become a maintenance problem
(duplication of properties throughout the code), one possible design
is to just put a blanket kwargs at the end and define an Artist update
method to look like (freestyle coding here...)

def update(self, **kwargs):
    for key, val in kwargs.items():
        func = getattr(self, 'set_'+key, None)
        if func is None or not callable(func): continue
        func(val)
        

Then we could do in the legend class

   for o in lines+texts+patches: o.update(kwargs)

The downside of course is that this fails silently if the user
provides a bad kwarg.  The upside is it is a very easy, clean
implementation that scales with the addition of new setters to the
underlying objects.


JDH