How can I define __getattr__ to operate on all items of container and pass arguments?
jlconlin at gmail.com
Tue Feb 15 22:58:11 CET 2011
On Tuesday, February 15, 2011 1:44:55 PM UTC-7, Chris Rebert wrote:
> On Tue, Feb 15, 2011 at 12:29 PM, Jeremy <jlco... at gmail.com> wrote:
> > I have a container object. It is quite frequent that I want to call a function on each item in the container. I would like to do this whenever I call a function on the container that doesn't exist, i.e., the container would return an attribute error.
> > For example
> > class Cont(object):
> > def __init__(self):
> > self.items = 
> > def contMethod(self, args):
> > print("I'm in contMethod.")
> > def __getattr__(self, name):
> > for I in self.items:
> > # How can I pass arguments to I.__dict__[name]?
> > I.__dict__[name]
> > The trouble I'm getting into is that I can't pass arguments to the attributes in the contained item. In the example above, I can't pass 'abc' to the 'itemMethod' method of each item in the container.
> > Does someone know how I can accomplish this?
> Recall that:
> is basically equivalent to:
> _a = x.y
> So the arguments haven't yet been passed when __getattr__() is
> invoked. Instead, you must return a function from __getattr__(); this
> function will then get called with the arguments. Thus (untested):
> def __getattr__(self, name):
> def _multiplexed(*args, **kwargs):
> return [getattr(item, name)(*args, **kwargs) for item in self.items]
> return _multiplexed
Perfect, that's what I needed. I realized that I didn't have the arguments to the function, but couldn't figure out how to do it. This works like a charm. Thanks a lot!
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