dynamic class instantiation

[Kent Johnson]

Ognen Duzlevski wrote:
> Volker Grabsch <volker_grabsch at v.notjusthosting.com> wrote:
>>I'm sure you could replace 2/3 of your code with something much simpler
>>(and shorter!) just by not inventing a new language and using the power
>>of Python instead.
> 
> 
> Hi Volker,
> 
> I appreciate your comments. Basically, the reason why this code generator
> exists is the fact that I do not want to hard-code the resulting xml in 
> any way. The users of the web/db framework of which this solution is part of
> might like the "web page" definition I offer them, but, some might want to extend it.
> While dom allows me to traverse an xml hierarchy - it does not allow me to
> give "meaning" to the tags. The only way to do that (for me) is to represent
> the tags as classes with containers containing other classes (tags) and so on. Since
> I do not know ahead of time what the tags will be - I need to generate the code
> to actually handle them.
> 
> Can you suggest a better approach or did you already do that and I just missed 
> it? :)

Instead of generating Python code and importing it, you could create the 
classes directly. You would still have your own language but no code 
generator.

For a very simple example, you could have a base class that initializes 
attributes from a class dictionary:
class DynamicInits(object):
   def __init__(self):
     self.__dict__.update(self.inits)

and a simple factory function that creates a subclass with an 
appropriate dict of initializers:
def classFactory(name, initializers):
   return type(name, (DynamicInits,), {'inits' : initializers})

In your original post you show this class:
class page(object):
	def __init__():
		self.name = None
		self.caption = None
		self.functions = []

With the above definitions, an equivalent class is created by calling
page = classFactory( 'page', { 'name' : None, 'caption': None, 
'functions' : []} )

Kent