Grant Edwards wrote:
On 2009-04-07, Scott David Daniels <scott.dani...@acm.org> wrote:
File "/usr/lib/python2.5/site-packages/ClientForm.py", line 2016, in
add_to_form
Control.add_to_form(self, form)
TypeError: unbound method add_to_form() must be called with FancyControl
instance as first argument (got CheckboxControl instance instead)
OK, that is one of the problems with monkey-patching. What happened
is ClientForm apparently defines subclasses of Control such as
CheckboxControl.
Right. Control is just a base class, and changing it to a
"different" class after sub-classes have been defined pulls the
rug out from under things. Had I thought about it for a
minute, I should have known that would happen. The working
patch tweaks the class in-place, so it works OK.
The monkey-patching only happens after the ClientForm module
has been executed (first import), and the monkey-patching
happens after all of that. So now the "tack it into the
class" method looks a bit better if you cannot simply add your
requirement to the ClientForm source.
That's obviously the "right thing", but it makes portability
more of an issue (I would have to archive/distribute ClientForm
source and users would have to install the customized version
of ClientForm).
Of course there's always the chance that my version of
monkey-patching will stop working with a different version of
ClientForm. We'll burn that bridge when we come to it.
What you might use as a half-way measure:
class Mixin: # or class Mixin(object) if new-style:
def __eq__(self, other):
return (self.type == other.type
and self.name == other.name
and self.value == other.value
and self.disabled == other.disabled
and self.readonly == self.readonly)
def __ne__(self, other):
return not self.__eq__(other)
...(including FancyHTMLForm) ...
class FancyControl(MixIn, ClientForm.Control): pass
class FancyCheckboxControl(MixIn, ClientForm.CheckboxControl): pass
...
ClientForm.HTMLForm = FancyHTMLForm
ClientForm.Control = FancyControl
ClientForm.CheckboxControl = FancyCheckboxControl
--Scott David Daniels
scott.dani...@acm.org
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