On 9/18/20 6:41 PM, Guido van Rossum wrote:
> On Fri, Sep 18, 2020 at 6:19 PM Ethan Furman wrote:
>> So at this point, I think the choices are:
>>
>> Standard Enum
>> __repr__ __str__
>> <RegexFlag.IGNORECASE: 2> RegexFlag.IGNORECASE
>>
>> and
>>
>> Modified Converted Constant
>> __repr__ __str__
>> re.IGNORECASE 2
>>
>> I will admit I fancy the MCC variant more, but we should make a
>> choice and then be consistent.
>
> Hm, there's also what re actually does (tried in 3.8, 3.9 and 3.10):
> ```
> >>> import re
> >>> print(str(re.I))
> RegexFlag.IGNORECASE
> >>> print(repr(re.I))
> re.IGNORECASE
> >>>
> ```
Well, the `str(re.I) == "RegexFlag.IGNORECASE"` is due to a bug I just
fixed a couple days ago. The intent, according to a comment in the
issue, was that str() and repr() would return the same thing,
"re.IGNORECASE".
> I honestly think we've already lost consistency.
I counted roughly 25 Enums in the stdlib at this point, and only two of
them have modified reprs or strs; and one of those is an internal class.
It's worth noting that two others are buggy -- one is being fancy with
values and didn't get the custom __new__ correct, they other left in
some commas when converting from it's original data type.
Most of those 25 were created via [Enum|IntEnum]._convert_ .
> Possibly regular enums (Enum, IntEnum, IntFlag) should just all return
> "class.name" , e.g. 'Color.RED', for both str() and
> repr(), and "converted" enums should return "module.name
> ", e.g. 're.IGNORE' for both? It restores the rule
> of thumb, and it's not unusual. Maybe it's a new trend -- PEP 585's
> list[int] returns "list[int]" for both str() and repr(). :-)
We could certainly go that route. The value is readily available, even
if not printed by default.
> At the same time it's as old as Python -- for most builtins other than
> strings, repr() and str() are the same, and modeled after repr().
> Historically, I only introduced the difference between str() and
> repr() because of strings -- I wanted the REPL to clearly show the
> difference between the number 42 and the string '42', but at the same
> time I wanted both to print as just '42'.
Thank you for that -- it's an invaluable debugging tool which I have
been grateful for many times.
> Another brainstorm (or brainfart): maybe repr() should show the
> module/class and the name, and str() should only show the name. We'd
> then get
> ```
> >>> # Mock-up!
> >>> print(str(re.i))
> IGNORE
> >>> print(repr(re.i))
> re.IGNORE
> >>>
> ```
> and similar for Color.RED:
> ```
> >>> # Another mock-up!
> >>> print(str(Color.RED))
> RED
> >>> print(repr(Color.RED))
> Color.RED
> >>>
> ```
I think that's too terse -- the first bit, whether class or module, repr
or str, is very important -- especially if you have several enums using
some of the same names for their members.
--
~Ethan~
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