[Python-Dev] bpo-34595: How to format a type name?

Barry Warsaw barry at python.org
Tue Sep 11 20:21:01 EDT 2018

MRAB wrote on 9/11/18 16:06:
> On 2018-09-11 23:23, Victor Stinner wrote:
>> Last week, I opened an issue to propose to add a new %T formatter to
>> PyUnicode_FromFormatV() and so indirectly to PyUnicode_FromFormat()
>> and PyErr_Format():
>>     https://bugs.python.org/issue34595
>> I merged my change, but then Serhiy Storchaka asked if we can add
>> something to get the "fully qualified name" (FQN) of a type, ex
>> "datetime.timedelta" (FQN) vs "timedelta" (what I call "short" name).
>> I proposed a second pull request to add %t (short) in addition to %T
>> (FQN).
>> But then Petr Viktorin asked me to open a thread on python-dev to get
>> a wider discussion. So here I am.

+1 for adding format specs for the types, and for giving a consistent 
way to specify which you want.  %t (short) and %T (long) do seem like 
the logical choices, and I think in context it'll be pretty evident what 
they mean.

> Perhaps we could have a single format code plus an optional '#' for the 
> "alternate form":
> %T for short form
> %#T for fully qualified name

OTOH, if %T and variants meant "type" but %t mean something entirely 
different, that *would* probably be confusing.


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