__getitem__ method on (meta)classes

Bengt Richter bokr at oz.net
Tue Mar 15 17:43:46 CET 2005


On Mon, 14 Mar 2005 23:44:46 -0700, Steven Bethard <steven.bethard at gmail.com> wrote:

>Ron Garret wrote:
>> What I'm really trying to do is to create enumerated types such that if:
>> 
>> e1 = enum(lst) and v = e1(x)
>> 
>> then
>> 
>> (x in lst) and (e1[v] == x)
>
>Use a class with __call__ and __getitem__:
>
>py> class enum(object):
>...     def __init__(self, vals):
>...         self.vals = vals
>...     def __call__(self, val):
>...         return self.vals.index(val)
>...     def __getitem__(self, index):
>...         return self.vals[index]
>...
>py> lst = 'abcd'
>py> x = 'b'
>py> e1 = enum(lst)
>py> v = e1(x)
>py> (x in lst) and (e1[v] == x)
>True

For that, why not just

 class enum(list):
    def __call__(self, val): return self.index(val)

Regards,
Bengt Richter



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