[Python-ideas] Changing str(someclass) to return only the class name

[Nick Coghlan]

I don't think this line of argument is valid. Printing 1 and "1" produces
the same output, that's why repr() exists.

If someone wants debugging level detail, use repr(), just like the
interactive interpreter does.

--
Nick Coghlan (via Gmail on Android, so likely to be more terse than usual)
On Oct 22, 2011 5:33 PM, "Steven D'Aprano" <steve at pearwood.info> wrote:

> Nick Coghlan wrote:
>
>> On Sat, Oct 22, 2011 at 3:45 AM, Steven D'Aprano <steve at pearwood.info>
>> wrote:
>>
>>> Éric Araujo wrote:
>>>
>>>> Hi everyone,
>>>>
>>>> I’ve sometimes wished that str(someclass) were the natural way to get a
>>>> class name, for example when writing __repr__ methods.
>>>>
>>> someclass.__name__ seems much more natural to me.
>>>
>>> If you want the name of the class, ask for its name, not its string
>>> representation. Generally speaking, the string representation should tell
>>> you what sort of object it is (either explicitly or implicitly), not just
>>> its value.
>>>
>>
>> While that's an accurate description of the purpose of a "string
>> representation", the function that serves that purpose is repr(), not
>> str(). Éric's patch doesn't touch type.__repr__, only type.__str__.
>>
>> str() is different - it's the one which is designed for general human
>> consumption, and may omit some details if it makes sense.
>>
>
> Yes, I understand the difference between repr and str and the guidelines
> for them both. My argument is that for human consumption, str(MyClass)
> should continue to return something like "<class MyClass>" and not just
> "MyClass".
>
>
>  The use case that lead to the patch was actually string interpolation
>> rather than direct invocation of str(). There's a lot of object
>> representation code and error message formatting code that currently
>> uses "obj.__class__.__name__" or "type(obj).__name__" to plug into a
>> "{}" or "%s" placeholder in a format string.
>>
>
> Regardless of where or how you are using the name, if you explicitly want
> the name, you should ask for it explicitly rather than implicitly.
>
> Remember also that print(spam) will use str(spam). If you do this:
>
> >>> print(spam)
> something
>
>
> what would you expect spam is? My bet is that you expect it to be the
> string "something". With your suggestion, it could be either the string
> "something", a function named something, a module named something, or a
> class named "something" (if one uses __name__ rather than module.class
> name). I don't consider this helpful.
>
> I am aware that the string representation (using either __str__ or
> __repr__) of an object is not the definitive word in what the object really
> is. Using just print, one can't distinguish between a class and a string
> "<class '__main__.Spam'>", or for that matter between the string 2 and the
> int 2, and that arbitrary objects can return arbitrary strings.
> Nevertheless, I like the __str__ of classes, modules and functions just the
> way they are.
>
>
>
> --
> Steven
>
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