Dynamic generation of doc-strings of dynamically generated classes

[Mikael Olofsson]

Hi!

I've asked Google, but have not found any useful information there.

Situation: I have a base class, say

 >>> class base(object):
         ImportantClassAttribute = None

Now, I want to dynamically generate subclasses of base. That's not a 
problem. However, I very much want those subclasses to have individual 
doc-strings. More precicely, I want that important class attribute to be 
reflected in the doc-string. That's the problem. The only way I've 
managed to accomplish that is something like the following.

 >>> ImportantClassAttribute = 7
 >>> docString = 'The case %s.' % (ImportantClassAttribute,)
 >>> exec('''class new(base):
          """%s"""
          pass ''' % (docString,))
 >>> new.ImportantClassAttribute = ImportantClassAttribute
 >>> new.__doc__
'The case 7.'

This works as intended. The subclasses do get the doc-strings I want 
them to have, and I can live with this solution. But: This solution does 
not strike me as especially beautiful or readable. My first naïve 
attempt was instead the following.

 >>> class new(base):
	pass

 >>> new.ImportantClassAttribute = 7
 >>> new.__doc__ = ('The case %(ImportantClassAttribute)s.'
	       % new.__dict__)

Traceback (most recent call last):
   File "<pyshell#35>", line 1, in -toplevel-
     new.__doc__ = ('The case %(ImportantClassAttribute)s.'
TypeError: attribute '__doc__' of 'type' objects is not writable

This is readable to me, but apparently not the way to go, since I'm not 
allowed to replace the doc-string like this. I've also tried a number of 
other ways, but they all stumble on similar reasons.

Any ideas? Am I stuck with the clumsy exec-solution, or are there other 
ways to dynamically generate doc-strings of classes?

/MiO