How best to dynamically define methods (and functions)?

[Kenneth McDonald]

I can see an obvious but hacky way to define a Python function at
runtime. I can't see any obvious way to add a method to a class at
runtime (though I'm sure one could do just about anything by digging
into the metaclass stuff, which I will do if needed). But pointers to
cleaner or easier existing ways to do this would be most appreciated.

In case it's of interest in the context of the question, I need to
define a largish set of functions (and similar methods) that define a
XML-type markup language. Most of these functions will just be of the form

def fun(...):
return Node('fun', ...)

so it'd definitely be nice to just create most of them automatically,
and only do the special cases by hand.
Many thanks,
Ken

[Diez B. Roggisch]

Kenneth McDonald schrieb:

I can see an obvious but hacky way to define a Python function at
runtime. I can't see any obvious way to add a method to a class at
runtime (though I'm sure one could do just about anything by digging
into the metaclass stuff, which I will do if needed). But pointers to
cleaner or easier existing ways to do this would be most appreciated.

In case it's of interest in the context of the question, I need to
define a largish set of functions (and similar methods) that define a
XML-type markup language. Most of these functions will just be of the form

def fun(...):
return Node('fun', ...)

so it'd definitely be nice to just create most of them automatically,
and only do the special cases by hand.

Then don't do it that way, but use __getattr__. It will exactly do what
you want:
class Foo(object):
def __getattr__(self, name):
return Node(name, ....)
def some_node(self):
... # hand coded stuff
Diez