On Fri, Apr 30, 2021 at 9:06 AM David Álvarez Lombardi <alvarezdqal@gmail.com> wrote:

I propose a syntax for constructing/filtering strings analogous to the one available for all other builtin iterables. It could look something like this.

>>> dirty = "f8sjGe7"
>>> clean = c"char for char in dirty if char in string.ascii_letters"
>>> clean
'fsjGe'

Currently, the best way to do this (in the general case) seems to be the following.
>>> clean = "".join(char for char in dirty if char in string.ascii_letters)

If a feature like this is useful -- and I'm not sure it is -- there is a much better way to do this IMHO. Add a new format converter to the syntax for replacement fields:

>>> f"{c for c in dirty if c in string.ascii_letters !j}"

'fsjGe'

where !j means join. It could optionally take a separator string as in this example:

>>> f"{chr(65 + i) for i in range(4) !j('-')}"

'A-B-C-D'

--- Bruce