In article <m24otg3hkk....@cs.uu.nl>, Piet van Oostrum <p...@cs.uu.nl> wrote:
>>>>>> Lawrence D'Oliveiro <l...@geek-central.gen.new_zealand> (LD) wrote:
>
>>LD> In message <h3bogf$oo...@panix3.panix.com>, Aahz wrote:
>
>>Aahz> class AttrDict:
>>Aahz> def __getitem__(self, key):
>>Aahz> return getattr(self, key)
>
>>LD> OK, let's try it:
>
>>LD> >>> c = {}
>>LD> >>> c["x"] = 3
>>LD> >>> c.x = 4
>>LD> Traceback (most recent call last):
>>LD> File "<stdin>", line 1, in <module>
>>LD> AttributeError: 'dict' object has no attribute 'x'
>>LD> >>> class AttrDict:
>>LD> ... def __getitem__(self, key):
>>LD> ... return getattr(self, key)
>>LD> ...
>>LD> >>> c.x = 4
>>LD> Traceback (most recent call last):
>>LD> File "<stdin>", line 1, in <module>
>>LD> AttributeError: 'dict' object has no attribute 'x'
>
>>LD> Nope, still doesn't work...
>
>Of course you need c = AttrDict()
Absolutely -- Lawrence really needs to learn to do his own debugging.
>And to get c.x = 4 working you also need a __setitem__.
Nope. You do need __setitem__ so that this works:
c['x'] = 4
>And to get c["x"] working AtrrDict should subclass dict:
Definitely not. There's a perfectly good dict inside a regular class
instance already. The only reason to subclass from dict is so that you
get all the dict methods for free; however, the cost is that you get
ugly bugs because of e.g.
c['update'] = 'foo'
Overally, I think it's much better/safer to explicitly pull the dict
methods you want to use.
--
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until you hire an amateur." --Red Adair
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