En Fri, 03 Oct 2008 11:03:22 -0300, TP <[EMAIL PROTECTED]>
escribió:
I would like to be able to specialize an existing class A, so as to
obtain a
class B(A), with all methods of B being the methods of A preceded by a
special method of B called _before_any_method_of_A( self ), and followed
by
a special method of B called _after_any_method_of_A( self ).
The goal is to avoid to redefine explicitly in B all methods of A.
Is this possible in Python?
Sure. After reading this (excelent!) article by M. Simionato
http://www.phyast.pitt.edu/~micheles/python/documentation.html you should
be able to write a decorator to make any method into a "sandwich"
(probably based on his "trace" example). Your code would look like this:
@decorator
def sandwich(f, self, *args, **kw):
self.before()
f(self, *args, **kw)
self.after()
class A:
@sandwich
def foo(self):
...
@sandwich
def bar(self, x):
...
Ok, but then you have to explicitely decorate every method. To avoid this,
you may use a metaclass; this article by Michael Foord explains how:
http://www.voidspace.org.uk/python/articles/metaclasses.shtml#a-method-decorating-metaclass
That's all!
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
