David Isaac wrote:
>> Alan Isaac wrote:
>>> I have a subclass of dict where __getitem__ returns None rather than
>>> raising KeyError for missing keys. (The why of that is not important
> for
>>> this question.)
>
> "Bruno Desthuilliers" <[EMAIL PROTECTED]> wrote:
>> Well, actually it may be important... What's so wrong with d.get('key')
>> that you need this behaviour ?
>
> I want to use the mapping with string interpolation.
>
Well, this makes sens... But then why not use a plain dict to collect
data, and wrap it in a special one just before using it for
interpolation ? ie:
class MyDictWrapper(object):
def __init__(self, d, default=None):
self._d = d
self._default = default
def __getitem__(self, key):
return self._d.get(key, self._default)
def render(d):
tpl = "%(who)s says '%(say)s' and the %(what)s is %(state)s."
return tpl % MyDictWrapper(d)
This would avoid any potential trouble with using a strange kind of dict
in other parts of the code...
My 2 cents...
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