[Python-ideas] Dict-like object with property access

Ethan Furman ethan at stoneleaf.us
Mon Jan 30 20:23:35 CET 2012

Antoine Pitrou wrote:
> On Mon, 30 Jan 2012 12:49:54 -0600
> Massimo Di Pierro
> <massimo.dipierro at gmail.com> wrote:
>> Trying to make sure I understand where we disagree and perhaps explain my problem better. For me this has very little to do with dictionaries.
>> STEP 2) We can now overload the [] to make the dynamic attributes accessible in an alternative syntax:
>>     class Dummy(object):
>>           def __getitem__(self,key): return getattr(self,key)
>>           def __setitem__(self,key,value): return setattr(self,key,value)
>>     d = Dummy()
>>     d.something = 5
>>     d['something'] = 5
>>     print d.something
>>     print d['something']
>> STEP 3) Is anybody calling this un-pythonic?
> Yes. You don't need both kinds of accesses.

Sure you do -- as soon as 'something' can be passed in via a variable:

def some_func(name):
     print(d.name)  # uh, no
     print(d[name]) # okay, this works

And when you are working with known objects (not passed in names):

def some_other_func():

Okay, *need* might be too strong, as you could get by with [] access -- 
but . access is so much nicer when possible (saves three characters, 
which can make a difference for those of us with wimpy wrists!).


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