On Fri, 04 Feb 2011 11:17:39 -0800, Marc Aymerich wrote:
> Hi!
> I need to create a pretty complex class at runtime. something like this
> one:
>
> (note: "...." means that the number of attributes can be variable)
>
> class VirtualUserLimitForm(ModelForm):
> swap_limit = forms.CharField(max_length=100,
> initial=monitor1.default_limit)
> memory_limit = forms.CharField(max_length=100,
> initial=monitor2.default_limit)
> ...
[...]
> I can generate all the needed code as string and then use exec(), but it
> seems ugly to me. I'm wondering if there is another way more elegant to
> do that? metaclasses maybe? What is your recommendation?
Just add in the class attributes you want after creating the class.
class VirtualUserLimitForm(ModelForm):
pass
f = forms.CharField # alias for brevity
for name, value in [
('swap_limit', f(max_length=100, initial=monitor1.default_limit)),
('memory_limit', f(max_length=100, initial=monitor2.default_limit)),
('spam', 'spam spam spam spam'),
('eggs', 'fried sunny side up'),
]:
setattr(VirtualUserLimitForm, name, value)
There's probably a name for this sort of technique, and an entire chapter
in "Design Patterns For People With Too Much Time On Their Hands" (15th
edition), but I don't remember it :)
--
Steven
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