On 2009-10-31, Steven D'Aprano <st...@remove-this-cybersource.com.au> wrote:
>>> Idiomatic Python is to use CamelCase for classes.
>> Can you point me to a discussion on Idiomatic Python, CamelCase and
>> other matters?
>
<...> See PEP 8:
>
> http://www.python.org/dev/peps/pep-0008/
Got it. Thanks.
>
>>> invalid parameter shouldn't raise the same error as failing an
>>> attribute look-up. That's misleading and confusing.
>>
>> What error class or other approach do you recommend?
>
> Unless you have a good reason for doing something different, do what
> Python built-ins do:
>
>>>> int('123', parrot=16)
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: 'parrot' is an invalid keyword argument for this function
Understood. I kyped that method from from an open source library module
and have been using it ever since.
>
>>> I also should point out that your trick will fail if you are using
>>> __slots__.
>> ??. Will research that. Elaborate if you wish.
>
> __slots__ are an optimization for making objects smaller than normal if
> you have many millions of them:
>
> http://docs.python.org/reference/datamodel.html#slots
Thanks.
<....>
>
>> If the class grows - and I expect it will - I'd prefer to stick with
>> the keywords approach. That approach also allows me to use a
>> dictionary to initialize the object.
>
> You can still do that with named parameters.
>
<...>
>>>> class Parrot:
> ... def __init__(self, name='Polly', colour='blue',
>>>> p = Parrot("Sparky", 'white', "Cockatoo")
>>>> data = dict(colour='red', name='Fred', foo=1)
>>>> p = Parrot(**data) # raise an error with bad input
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: __init__() got an unexpected keyword argument 'foo'
<...> OK. That makes sense. You have made a believer of me.
I really appreciate all the time you have taken with this.
Many programmers I know stay away from 'lists' such as this, because
they are afraid to show their ignorance. Me, I'm fearless, and I have
learned a lot that I might not have otherwise.
take care
--
Tim
t...@johnsons-web.com
http://www.akwebsoft.com
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