By the way,
I think by approving
a = b if condition else c
used to avloind
if condition:
a = b
else:
a = c
which is dealing with same psychological problem, Guido also recognizes some
need...
Is it redundant according to your criteria, yes I would say:
a = {True: a, False: c}[condition]
or
a = [c, a][condition]
would yield exactly the same even in one sentence....
Cheers,
@
at wrote:
> My comments below.
>
> Kind regards,
> @
>
>
> Carl Banks wrote:
>
>> at wrote:
>>> Well, all I can say that for me as a user it would make sense...
>>
>> Which is, like, step one out of a hundred for getting a syntax change
>> into the language.
>>
>>> Curiosity: in what sense is it redundant?
>>
>> It creates syntactical support for two different ways to do something.
>> If your plan were adopted, then we'd have two different spellings for
>> the same thing:
>>
>> for i in a:
>> if i != 0:
>> use(i)
>>
>> for i in a if i != 0:
>> use(i)
>
> With the current Python syntax, I can create for every two lines of code a
> dozen alternative implementations:
>
> # example 1
> a = {}
> a['b'] = 'c'
>
> versus:
> a = {'b': 'c'}
>
>
> # example 2
> l = []
> for l in some_list:
> if some_condition:
> l.append(l)
>
> versus:
> l = []
> for x in some_list:
> if some_condition:
> l = l + [x]
>
> or:
> l = [x for x in some_list if some_condition]
>
> (the beautiful one)
>
> So your argument doesn't mean much I would say!
>
>>
>> Now, redundant syntax isn't a deal breaker by itself. You have to ask
>> what is buys you. In this case, all it does is save you a single level
>> of indentation--that's it. There's no performance benefit. It doesn't
>> simplify logic. It doesn't make the code any more readable of clear.
>> It's only a minor improvement in conciseness. It hardly saves any
>> typing (unless you indent by hand). Even its one clear benefit, saving
>> indentation, is something you can already get with "if not x:
>> continue".
>
>
> Well there is a clear performance benefit, or more precisely a
> productivity benefit. And -please- do not underestimate this for a
> language like Python, which has many supporters due to its perceived and
> high productivity and challenged on this point by languages like Ruby.
>
> 'for x in some_list if some_condition:'
>
> is psychological very strong, because the brain will most likely treat the
> in the same way as :
>
> for every apple in the fruitbasket take one if green
>
>
> Basically upon reading this first line you know exactly to what list of
> items your next section of code applies.
>
> But again everything is a matter of taste and I assume that's why the
> change control body is put into the hand of one person.
>
>
>
>> Considering how little this syntax change buys, it really doesn't make
>> a lot of sense for a language that places high emphasis on avoiding
>> redundancy.
>>
>>
>>> All solution/workarounds I have seen so far involve creation of new
>>> lists (subsets) adding to more processing/computation/memory usage.
>>> Redundant suggests that you know alternatives that don't do that.
>>>
>>> Does Guido ever change his mind?
>>
>> Yes, but I guarantee "it makes sense for me" isn't going to convince
>> him. By the way, I'd suggest when posting to comp.lang.python and/or
>> python-list in the future, you put your replies beneath the quoted text
>> for the benefit of any future readers (not to mention present readers).
>>
> I hope this this thread will support the "it makes sense for me" with
> arguments. Again it is not my intention to fight windmills, but to see if
> there are strong arguments against it on one hand and if there supporters
> on the other hand.
>
>
>>
>> Carl Banks
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