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

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(a)redhat.com&gt; >>> --- >>> 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.