Cool object trick
steve at holdenweb.com
Fri Dec 17 16:10:51 CET 2004
Fredrik Lundh wrote:
> Steve Holden wrote:
>>>Certainly makes writing 'print obj.spam, obj.spam, obj.eggs, obj.bacon,
>>>obj.sausages, "and", obj.spam' a lot easier ;-)
>>Of course this whole thing of substituting attribute access for dictionary keys only works as long
>>as the keys are strings with the same syntax as Python identifiers, so one shouldn't go completely
> unless you're willing to use getattr() for thos oddball cases, of course.
> >>> class Dummy:
> ... pass
> >>> x = Dummy()
> >>> setattr(x, "spam&egg", "hello")
> >>> getattr(x, "spam&egg")
> >>> x.spam&egg
> Traceback (most recent call last):
> File "<stdin>", line 1, in ?
> AttributeError: Dummy instance has no attribute 'spam'
> but seriously, turning container elements into attributes should only be done
> if it makes sense from a design perspective. (and vice versa; you shouldn't
> use a dictionary if an object would make more sense -- but attribute abuse
> is a lot more common)
Really we are talking about the outer limits here. Anyone preferring
setattr(x, "spam&egg", "hello")
x["spam&egg"] = "hello"
when it isn't necessary clearly doesn't share our two principal
attributes: an elegant sense of design, fine knowledge of Python and an
Sorry: out *three* principal attributes. Bugger, I'll come in again.
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/
Holden Web LLC +1 703 861 4237 +1 800 494 3119
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