typechecks: just say no! (was Re: Determining Types)

David C. Ullrich ullrich at math.okstate.edu
Mon Sep 10 00:47:26 CEST 2001


On Sun, 09 Sep 2001 05:38:50 GMT, Guido van Rossum <guido at python.org>
wrote:

>ullrich at math.okstate.edu (David C. Ullrich) writes:
>
>> But in other places it's good to be able to refer to
>> fields with non-literal names, so I add a __getitem__
>> so that rec['thisfield'] returns rec.thisfield. 
>> (Actually the main reason I want this is so that I
>> can use a Rec as a mapping in a string format thing:
>> 
>> 'Your name is %(Name)s' % rec)
>> 
>> In yet other places I want to iterate over the fields 
>> of a record, as in
>> 
>> for key, value in rec:
>> 
>> So in __getitem__ I check the type of index, returning
>> getattr(self, index) if index is a string and saying
>> 
>> fieldname=self.__fieldnames__[index]
>> return (fieldname, getattr(self, fieldname))
>> 
>> if index is an integer.
>
>In 2.2, you can define an iterator rather than overloading __getitem__.

So I've heard - seems much better. (Was serious at the top
of the post when I said I felt bad about the overloading.
Well, it was the type-checking I mentioned but it's actually
the overloading that bothered me.)

>--Guido van Rossum (home page: http://www.python.org/~guido/)


David C. Ullrich



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