I i need a decorator that adds a local variable in the function it decorates, probably related with nested scopes, for example:
def dec(func): def wrapper(obj = None): if not obj : obj = Obj() <bind obj to func> return func()
return wrapper()
@dec() def fun(b): obj.desc = 'marked' obj.b = b return obj
so the call to fun : fun(obj = myobj,'b argument') or fun('b argument')
So the function "fun" assumes it has an obj instance and other instance objects computed by the decorator, this decorator will be like a generic factory for this kind of functions,which depends on the decorator to work.
For a byte-code hack that does something similar, see the recent thread:
http://mail.python.org/pipermail/python-list/2005-March/270324.html
It can do something like:
py> class Object(object): ... pass ... py> @presets.presets(obj=Object()) ... def fun(b): ... obj.desc = "marked" ... obj.b = b ... return obj ... py> fun(1) <__main__.Object object at 0x01162BD0> py> fun(1).b 1
But note that you then only have a single instance for all calls to the function:
py> fun(1) is fun(2) True
Have you considered using OO here? You might find that this is more easily written as:
py> class Object(object): ... pass ... py> class fun(object): ... def __new__(self, *args): ... if len(args) == 2: ... obj, b = args ... elif len(args) == 1: ... obj, [b] = Object(), args ... else: ... raise TypeError ... obj.desc = "marked" ... obj.b = b ... return obj ... py> myobj = Object() py> fun(myobj, 2) <__main__.Object object at 0x01162E30> py> myobj.b 2 py> obj = fun(1) py> obj.b 1
This doesn't use any bytecode hacks, but I'm still not certain it's really the way to go. What is it you're trying to write this way?
STeVe -- http://mail.python.org/mailman/listinfo/python-list
