On Sat, Mar 13, 2010 at 12:10 PM, Jon Clements <jon...@googlemail.com> wrote: > On 13 Mar, 16:42, Jack Diederich <jackd...@gmail.com> wrote: >> On Sat, Mar 13, 2010 at 11:19 AM, Jon Clements <jon...@googlemail.com> wrote: >> > This is semi-experimental and I'd appreciate opinions of whether it's >> > the correct design approach or not. It seems like a good idea, but it >> > doesn't mean it is. >> >> > I have a class 'A', this provides standard support functions and >> > exception handling. >> > I have 'B' and 'C' which specialise upon 'A' >> >> > What I'd like to achieve is something similar to: >> >> > @inject(B): >> > def some_function(a, b): >> > pass # something useful >> >> > The name 'some_function' is completely redundant -- don't need it, >> > don't actually care about the function afterwards, as long as it >> > becomes a __call__ of a 'B' *instance*. >> >> > I've basically got a huge list of functions, which need to be the >> > callable method of an object, and possibly at run-time, so I don't >> > want to do: >> >> > class Something(B): >> > def __call__(self, etc.. etc...): >> > pass # do something >> >> > I've got as far as type(somename, (B,), {}) -- do I then __init__ or >> > __new__ the object or... >> >> > In short, the function should be the __call__ method of an object that >> > is already __init__'d with the function arguments -- so that when the >> > object is called, I get the result of the the function (based on the >> > objects values). >> >> I'm not sure exactly what you are asking for, but if what you want is >> a bunch of different objects that vary only by their class's __call__ >> you could do it with a function that returns a new class based on A >> but with a new __call__: >> >> def make_new_call_class(base_class, call_func): >> class NewClass(base_class): >> def __call__(self, *args, **kw): >> return call_func(self, *args, *kw) >> return NewClass >> >> or the return could even be NewClass() [return an instance] if this is >> a one off. >> >> That said, I'm not really sure what this behavior is good for. >> >> -Jack > > Cheers Jack for the response. > > The behaviour is to not derive from a class, but rather allow > the decorators to do so... so I would like to iterate over > a list of functions (don't care what they're called) and then > inject the function as a method. If needs be at run-time. > > Say I have 1000 functions (okay, admittedly over quoted), but > I don't want every programmer to inherit from 'B' or 'C', but > to 'inject'. So the idea is that classes are pre-defined, have > predictable behaviour, *except* the __call__ is different. > > You are correct in this. Why do I want that behaviour? -> > > - It's easier, no inheriting from a class, when needs not. > - Some integrity (anyone can define a function and 'inject' to the > Management class) > - Easier maintainability - maybe :) > > for i in function_list: > i = inject(function_list) > > At the end of the day: > def blah(x, y, z): > pass > > That should be the callable of the object.
I'm still not sure why you are trying to do this, but you can do it with delegation. Have the parent class's __call__ look for an instance attribute named call_this and then call it, ex/ class A(): def __call__(self, *args, **kw): self.call_this(*args, **kw) # we grab this off the instance ob = A() def my_func(*stuff): pass ob.call_this = my_func -Jack -- http://mail.python.org/mailman/listinfo/python-list