[Python-ideas] get() method for list and tuples

[David Mertz]

On Tue, Feb 28, 2017 at 10:10 AM, Sven R. Kunze <srkunze at mail.de> wrote:

> Yes, and easily written as above.  What significant advantage would it
> have to spell the above as:
>
>     x = alist.get(pos, default_val)
>
> It's a couple characters shorter in the proposed version.  I guess I'll
> concede that needing the odd indexing at the end to get the scalar is
> slightly ugly.
>
> 1. advantage: it looks like dict access -> allows duck typing (oh how
> often I'd missed that)
> 2. advantage: no try except
> 3. advantage: no weird workaround with slices and additional item access
>

How often would you duck-type "access either an integer position or a named
key in a collection?"

I'm all for duck typing, but it feels like those are a pretty different
pattern.  For example, I know that if a list has something at index 10 it
also has something at index 9.  I absolutely *do not* know that if a dict
has something at key 'g' it also has something at key 'f'.


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