On 2017-03-09 06:07, Steven D'Aprano wrote:
On Wed, Mar 08, 2017 at 08:29:19PM -0800, Alex Kleider wrote:Things like this can usually be broken down into their component parts but I've been unsuccessful doing so: def f(lst): res = {} for item in lst: method_res = res.setdefault(item, []) res.method_res.append(item) # res.setdefault(item,[]).append(item) return list(res.values()) res.method_res.append(item) AttributeError: 'dict' object has no attribute 'method_res' Python must be doing some trickery behind the scenes.Why do you say that? I'm not sure what result you expected, or what you are trying to do, but you have: res # a dict res.method_res No surprises that this fails with AttributeError. Dicts do not have an attribute or method called "method_res". Perhaps you meant to write: # not this # res.method_res.append( ... ) # this instead method_res.append( ... ) although part of the confusion is that "method_res" is a poorly chosen name. It isn't a method, it is a list.
Thanks again, Steven. I confess to having intended to write res.method_res.append(... but your response made me realize that because lists are mutable it all works without the res. prefix.
I chose method_res to refer to the fact that it is the result of a method call. A poor choice I admit.
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