[issue32626] Subscript unpacking raises SyntaxError
New submission from Ben Burrill : PEP 448 defines unpacking generalizations for tuples. However, this does not currently work for subscripted tuples that are not delimited by parentheses. Current behavior (Tested on 3.6/3.7a4): >>> class Subscriptable: ... def __getitem__(self, item): ... return item ... >>> ss = Subscriptable() >>> >>> 1, 2, 3 (1, 2, 3) >>> ss[1, 2, 3] (1, 2, 3) >>> *range(5), 42 (0, 1, 2, 3, 4, 42) >>> ss[*range(5), 42] # This should be the same as above File "", line 1 ss[*range(5), 42] ^ SyntaxError: invalid syntax >>> ss[(*range(5), 42)] # Workaround (0, 1, 2, 3, 4, 42) -- components: Interpreter Core messages: 310447 nosy: Ben Burrill priority: normal severity: normal status: open title: Subscript unpacking raises SyntaxError type: behavior versions: Python 3.7 ___ Python tracker <https://bugs.python.org/issue32626> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue32626] Subscript unpacking raises SyntaxError
Ben Burrill added the comment: Yeah, but in this case, you don't need parentheses unless you use unpacking. That is unexpected behavior. -- ___ Python tracker <https://bugs.python.org/issue32626> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue31707] Irrational fractions
New submission from Ben Burrill : fractions.Fraction enforces its numerator and denominator to be rational. This is a good idea for purely numeric fractions, but the abstractions that fractions.Fraction offers would also be useful for more abstract fractions. Some places where this might be useful would be fractions of polynomial types or fractions with abstract irrational numeric types, like F(SquareRoot(3), 2). This could be accomplished by having a more general Fraction superclass or by removing the requirement of rationality from fractions.Fraction. It is not trivial to create a subclass of Fraction that does this because the operators are hardcoded to use Fraction and initiation is done in __new__. -- components: Library (Lib) messages: 303788 nosy: Ben Burrill priority: normal severity: normal status: open title: Irrational fractions type: behavior versions: Python 3.6 ___ Python tracker <https://bugs.python.org/issue31707> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue31707] Irrational fractions
Change by Ben Burrill : -- nosy: +mark.dickinson, rhettinger ___ Python tracker <https://bugs.python.org/issue31707> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue31707] Irrational fractions
Ben Burrill added the comment: The core operators, like multiplication and division, should work for any type that defines the right operators. Hashing is tricky, and reducing the fraction is pretty much off the table. This is why I suggested a superclass. I'll try making a patch sometime soon. I am aware of sympy and am not proposing that the standard library stray too far into symbolic mathematics. Sympy's re-invention of the fraction makes sense given sympy's scope, but simpler libraries that offer other abstract math features (like one that just implemented a simple Polynomial type) would benefit from using fractions.Fraction. This change would probably make it so that sympy symbols worked with fractions.Fraction, which although unnecessary, might be nice. -- ___ Python tracker <https://bugs.python.org/issue31707> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
