[libvirt] [PATCH] check-symfile: Use pythonesque string formatting instead of perl

[Erik Skultety]

On Mon, Nov 25, 2019 at 05:17:54PM +0100, Michal Privoznik wrote:
> On 11/25/19 4:58 PM, Erik Skultety wrote:
> > On Mon, Nov 25, 2019 at 04:37:36PM +0100, Peter Krempa wrote:
> > > Commit d30a1ad0443 translated the symbol file checker from perl to
> > > python by doing a literal translation in most cases. Unfortunately one
> > > string formatting operation was not really translated into python
> > > leaving users with non-helpful error:
> > >
> > > 'Symbol $1 is listed twice'
> > >
> > > Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> > > ---
> > >   scripts/check-symfile.py | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/scripts/check-symfile.py b/scripts/check-symfile.py
> > > index 0c02591991..34396b8623 100755
> > > --- a/scripts/check-symfile.py
> > > +++ b/scripts/check-symfile.py
> > > @@ -52,7 +52,7 @@ with open(symfile, "r") as fh:
> > >           line = line.strip(";")
> > >
> > >           if line in wantsyms:
> > > -            print("Symbol $1 is listed twice", file=sys.stderr)
> > > +            print("Symbol %s is listed twice" % line ,file=sys.stderr)
> >
> > Not a deal breaker, but IMO should at least the "new" syntax for string
> > formatting using the .format() method (works both with python 2 and 3).
> >
> > Ideally, we'd move to python 3.6+ (since 2 will die in about 2 months) and
> > started using string interpolation (or f-strings if you want).
>
> Well, looks like we are not using that anywhere. And frankly, f-strings are
> horrible. This is the most readable style for us, C developers IMO.

Can you be more specific on what exactly is horrible about f-strings? IMO it's
actually very intuitive way of formatting strings unlike using the '%'
formatting sign where depending on whether you have 1 or multiple arguments you
may or may not need to use a tuple. F-strings are also a bit faster than the
other formatting methods and because they're evaluated during runtime, you can
evaluate arbitrary expressions, even call functions.

Erik