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

On Tue, Nov 26, 2019 at 09:48:31AM +0100, Michal Privoznik wrote: > On 11/26/19 9:24 AM, Erik Skultety wrote: > > 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. > > That's exactly what I find horrible. Just consider the following example: > > print(f'a={f(x,n):d}, b={g(x,n):d}') > > IMO the following is more readable: > > print("a=%d, b=%d" % (f(x,n), g(x,n))) > > Once again, I'm talking about C developers (me specifically). I don't doubt > that an experienced python developer finds f-strings a step forward. I've plenty of python dev experiance and I still think f-strings are a horrible regression in design. IMHO it is a good thing to have the parameters visually separated from the string, as it makes it clearer to read the string being formatted.