Pylint: Consider nudging users towards using f-strings

[NeilGirdhar]

Python 3.5 is end-of-life in September 2020. Since Python 3.6 introduced f-strings, there is no good reason to interpolate _literal strings_ with the string interpolation operator

'Python %f' % version

or the format method

'Python {}'.format(version)

—except when the arguments involve unpacking:

'Python {} or {}`.format(*versions)

Can we consider a pylint warning to nudge users towards using f-strings when possible? It would be extremely helpful to write the f-string for them. For example:

a.py:1:0: W999: Not using f-string: f"Python {version}" (not-using-fstring)

What do you think?

[TylerYep]

Seconded, especially since f-strings are a lot faster in practice as well.

[Pierre-Sassoulas]

It seems reasonable to me. I just think that the message should be a convention instead of a warning.