Re: [Jython-users] java.util.map Compatible data structure in python

[David H. <dav...@gm...>]

I can think of one thing that would be awkward from a backwards
compatibility standpoint.  Currently, if m is a Map that does not
contain "foo" as a key, then in Python code m['foo'] returns None.  If
m is a dict that does not contain "foo" as a key, then m['foo'] throws
a KeyError.  So, if m is a Map *and* a dict, what does m['foo'] do?
There may be existing code written to handle both Maps and dicts that
tests whether m is a Map and then uses m[k] == None to test whether k
is in m.  It's not the best way to implement this functionality, and
it's wrong if k is mapped to null, but I imagine such code exists and
works fine in the field.

Personally, I say breaking this is worth it, but opinions will differ, I'm sure.

-David

On Wed, Apr 30, 2008 at 5:26 PM, Tim Gilbert <ti...@sk...> wrote:
> On a more general note about this dict versus Map stuff, can anyone
>  explain why the jython dict class doesn't simply implement
>  java.lang.Map?  It seems like such an obvious thing to do that I'm sure
>  there must be good reason why it hasn't been done, but I don't know what
>  that reason is.  Off the top of my head I can't think of any
>  functionality from the java version that the python version lacks, though.
>
>  Thanks
>  Tim
>
>
>
>
>
>
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