On Thu, Oct 13, 2016, at 16:59, Paul Moore wrote: > I don't (for the reasons raised before). But thank you for your > explanation, it clarifies what you were proposing. And it does so > within the *current* uses of the * symbol, which is good. But: > > 1. I'm not keen on extending append's meaning to overlap with extend's > like this.

## Advertising

I think the "append(*x)" bit was just a flourish to try to explain it in terms of the current use of * since you don't seem to understand it any other way, rather than an actual proposal to actually change the append method. > 2. Your proposal does not generalise to generator expressions, set > displays (without similarly modifying the set.add() method) or > dictionary displays. Basically it would make the following substitutions in the conventional "equivalent loops" generator yield => yield from list append => extend set add => update dict __setitem__ => update dict comprehensions would need to use **x - {*x for x in y} would be a set comprehension. > 3. *fn(x) isn't an expression, and yet it *looks* like it should be, > and in the current syntax, an expression is required in that position. > To me, that suggests it would be hard to teach. [1] I can think of another position an expression used to be required in: Python 3.5.2 >>> [1, *(2, 3), 4] [1, 2, 3, 4] Python 2.7.11 >>> [1, *(2, 3), 4] File "<stdin>", line 1 [1, *(2, 3), 4] ^ SyntaxError: invalid syntax Was that hard to teach? Maybe. But it's a bit late to object now, and every single expression on the right hand side in my examples below already has a meaning. Frankly, I don't see why the pattern isn't obvious [and why people keep assuming there will be a new meaning of f(*x) as if it doesn't already have a meaning] Lists, present: [x for x in [a, b, c]] == [a, b, c] [f(x) for x in [a, b, c]] == [f(a), f(b), f(c)] [f(*x) for x in [a, b, c]] == [f(*a), f(*b), f(*c)] [f(**x) for x in [a, b, c]] == [f(**a), f(**b), f(**c)] Lists, future: [*x for x in [a, b, c]] == [*a, *b, *c] [*f(x) for x in [a, b, c]] == [*f(a), *f(b), *f(c)] [*f(*x) for x in [a, b, c]] == [*f(*a), *f(*b), *f(*c)] [*f(**x) for x in [a, b, c]] == [*f(**a), *f(**b), *f(**c)] Sets, present: {x for x in [a, b, c]} == {a, b, c} {f(x) for x in [a, b, c]} == {f(a), f(b), f(c)} {f(*x) for x in [a, b, c]} == {f(*a), f(*b), f(*c)} {f(**x) for x in [a, b, c]} == {f(**a), f(**b), f(**c)} Sets, future: {*x for x in [a, b, c]} == {*a, *b, *c} {*f(x) for x in [a, b, c]} == {*f(a), *f(b), *f(c)} {*f(*x) for x in [a, b, c]} == {*f(*a), *f(*b), *f(*c)} {*f(**x) for x in [a, b, c]} == {*f(**a), *f(**b), *f(**c)} Dicts, future: {**x for x in [a, b, c]} == {**a, **b, **c} {**f(x) for x in [a, b, c]} == {**f(a), **f(b), **f(c)} {**f(*x) for x in [a, b, c]} == {**f(*a), **f(*b), **f(*c)} {**f(**x) for x in [a, b, c]} == {**f(**a), **f(**b), **f(**c)} _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/