[Python-Dev] Re: A small proposed change to dictionaries' "get" method

[M.-A. Lemburg]

Guido van Rossum wrote:
> 
> Marc-Andre writes:
> > The following one-liner already does what you want:
> >
> >       d[word] = d.get(word, []).append('world')
> 
> Are you using a patch to the list object so that append() returns the
> list itself?  Or was it just late?  For me, this makes d[word] = None.

Ouch... looks like I haven't had enough coffee today. I'll
fix that immediately ;-)

How about making this a method:

def inplace(dict, key, default):

    value = dict.get(key, default)
    dict[key] = value
    return value

>>> d = {}
>>> inplace(d, 'hello', []).append('world')
>>> d
{'hello': ['world']}
>>> inplace(d, 'hello', []).append('world')
>>> d
{'hello': ['world', 'world']}
>>> inplace(d, 'hello', []).append('world')
>>> d
{'hello': ['world', 'world', 'world']}

(Hope I got it right this time ;-)

-- 
Marc-Andre Lemburg
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