[Scons-dev] This morning's WTF moment

[Vasily]

To  test against True/False one should better implement __nonzero__, not
__eq__ or something :-) That way one could then use the form "if obj:", not
an ugly form of "if obj == True:".

Thanks,
Vasily
09 сент. 2014 г. 12:03 пользователь "Jean-Baptiste Lab" <
jeanbaptiste.lab at gmail.com> написал:

> Or wouldn't it be enough to simply mandate that exists() return something
> that can be tested against True/False?
> If that's the case, wouldn't a bit of wrapping around and implementing the
> __eq__/__neq__ descriptors (possibly __cmp__) be good enough so that we can
> get to the error description when needed (if False) without breaking
> existing usages?
>
> Or maybe I'm just missing the point, in which case I apologize ;)
>
> Cheers,
>
> JB
>
> On 9 September 2014 04:24, William Blevins <wblevins001 at gmail.com> wrote:
>
>> This might be obvious, but it the exception pattern not popular in python?
>> On Sep 8, 2014 9:19 PM, "Gary Oberbrunner" <garyo at oberbrunner.com> wrote:
>>
>>>
>>> On Mon, Sep 8, 2014 at 4:13 PM, Kenny, Jason L <jason.l.kenny at intel.com>
>>> wrote:
>>>
>>>> Ideally I always viewed this as a True False statement. I see you have
>>>> it returning a tuple.
>>>>
>>>>
>>>>
>>>> I only worry that I have seen a lot push with certain python developers
>>>> to say stuff like
>>>>
>>>>
>>>>
>>>> if not tool.exists():
>>>>
>>>>     # do something…
>>>>
>>>>
>>>>
>>>> This will not work as we will have a (True,””) or (False,””) return
>>>> API. This seems to me to more complex to use and understand. At the very
>>>> least east to trip up on. If we want an object returned. I think it will be
>>>> better to define a error object that can be tested as True or False vs
>>>> forcing tuple separation on returns values.
>>>>
>>>
>>> Excellent point.  The 'if not tool.exists()' pattern needs to work.
>>>  I'll rethink that.  Maybe something as simple as tool.exist_error() which
>>> can be called just after exists() returns False...
>>>
>>> --
>>> Gary
>>>
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>
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