Adding method to class at run-time: bad style?
invalid at invalid
Wed Apr 8 16:02:25 CEST 2009
On 2009-04-08, Gabriel Genellina <gagsl-py2 at yahoo.com.ar> wrote:
>>> class Mixin: # or class Mixin(object) if new-style:
>>> def __eq__(self, other):
>>> return (self.type == other.type ...
>>> def __ne__(self, other):
>>> return not self.__eq__(other)
>>> class FancyControl(MixIn, ClientForm.Control): pass
>>> class FancyCheckboxControl(MixIn, ClientForm.CheckboxControl): pass
>>> ClientForm.Control = FancyControl
>>> ClientForm.CheckboxControl = FancyCheckboxControl
>> That would work -- but there are probably 8 or 10 different
>> Control subclasses. It's a bit tedious mixing them all one at a
>> time, and you need more "inside" information (the names of all
>> the different subclasses).
> New style classes have a __subclasses__() method that could be used to
> find all of them (*at a certain moment*) -- but considering all the
> issues, I think that monkey-patching the base class is the "less bad"
> option in this case...
I agree. Inserting methods into the base class seems to be
working fine, and it's the least messy of the alternatives. I'd
submit a patch for ClientForm, but I don't know if my
definition of "equal" for a form/control is generally useful
enough to warrant being added to the package.
FWIW, I'm using it for automated regression-testing on a
product containing a web server. Basically, I perform an
operation on the product, and then check to make sure that only
certain web pages/form/controls changed in the manner they
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