[Python-ideas] Sort statement

[Chris Rebert]

On Sun, Jun 15, 2008 at 12:46 PM, Brandon Mintern <bmintern at gmail.com> wrote:
> On Sat, Jun 14, 2008 at 7:48 PM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
>> I don't think that sorting is a frequent enough operation
>> in general to justify having its own statement.
>
> Agreed.
>
>>> The main advantage is that it is impossible to make this mistake:
>>>
>>> x = y.sort()
>>
>> If you make that mistake, you find out about it very
>> quickly, and you learn not to make it again.
>
> Yes, but having .sort() return self would also solve this problem
> without anything as radical as introducing a new keyword and syntax.
> I'm not saying that this should be done, but I think this would be a
> much better alternative than the proposed sort syntax.

But that would be more confusing and make it seem to the newbie that
.sort() returns a *new* sorted list rather than sorting the list
in-place. Returning None (or not returning anything, which has the
same effect) is idiomatic in Python to indicate a method is a mutator.
And they'll quickly get a "TypeError: unsubscriptable object" and
learn this lesson if they use list.sort() incorrectly.

Although I admit, that error message could be improved. At least
including the object in question would be better, for instance:
TypeError: unsubscriptable object "None"
Or perhaps also changing "unsubscriptable" to something more
comprehensible to newbies:
TypeError: object "None" does not support the subscript operator


- Chris R.

>
> Brandon
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