bpo-44258: support PEP 515 for Fraction's initialization from string by skirpichev · Pull Request #26422 · python/cpython

the-knights-who-say-ni

I don't see any particular advantage to the rename.

Naming of patterns seems to be more consistent in this case: num/den vs num/denom.

But you are right, this is not related to the PR. I'll revert.

I prefer the version where we don't have the same local name referring to both a string and an int

~~I don't think there are. We have den/denom for strings and denominator - which is an integer.~~

This patch may be better:

diff --git a/Lib/fractions.py b/Lib/fractions.py
index 180cd94c28..1268b6bd27 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -26,7 +26,7 @@
     (?=\d|\.\d)                           # lookahead for digit or .digit
     (?P<num>\d*|\d+(_\d+)*)               # numerator (possibly empty)
     (?:                                   # followed by
-       (?:/(?P<denom>\d+(_\d+)*))?        # an optional denominator
+       (?:/(?P<den>\d+(_\d+)*))?          # an optional denominator
     |                                     # or
        (?:\.(?P<decimal>d*|\d+(_\d+)*))?  # an optional fractional part
        (?:E(?P<exp>[-+]?\d+(_\d+)*))?     # and optional exponent
@@ -115,9 +115,9 @@ def __new__(cls, numerator=0, denominator=None, *, _normalize=True):
                     raise ValueError('Invalid literal for Fraction: %r' %
                                      numerator)
                 numerator = int(m.group('num') or '0')
-                denom = m.group('denom')
-                if denom:
-                    denominator = int(denom)
+                den = m.group('den')
+                if den:
+                    denominator = int(den)
                 else:
                     denominator = 1
                     decimal = m.group('decimal')