Hi James Thank you for your message. I have some general, background comments. However, the question remains: Does your proposal sit well with the rest of Python?
By the way, I've just found a nice article: http://treyhunner.com/2018/03/tuple-unpacking-improves-python-code-readability/ You wrote > Currently, is <expr1> = <expr2> = <expr3> = <expr4> always equivalent > to <expr1> = <expr4>; <expr2> = <expr4>; <expr3> = <expr4>? It is very important, in this context, to know what we can assign to. We can assign to some expressions, but not others. Here are some examples >>> fn() = 4 SyntaxError: can't assign to function call >>> fn()[0] = 4 NameError: name 'fn' is not defined >>> 1 = 2 SyntaxError: can't assign to literal >>> None = None SyntaxError: can't assign to keyword When assigned to, the expression "(a, b)" has a special meaning. Strictly speaking, we are not assigning to a tuple. Hence >>> (fn()[1], a.b) = (0, 1) # Valid syntax. NameError: name 'fn' is not defined Finally, here's something that surprised me a little bit >>> x = [1, 2]; id(x) 140161160364616 >>> x += [3, 4]; id(x) 140161160364616 >>> x = (1, 2); id(x) 140161159928520 >>> x += (3, 4); id(x) 140161225906440 Notice that '+=' creates uses the same object when the object is a list, but creates a new object. This raises the question: Why and how does Python behave in this way? Finally, thank you for your stimulating idea. I think to take it forward you have to deal with two questions: 1. Does the proposal sit well with the rest of Python? 2. Does it IN PRACTICE bring sufficient benefits to users? Please note that Python deservedly has a reputation for being a readable language. Some will argue that allowing >>> (a, b) += (c, d) may bring benefits to the author of the line of code, but to the cost of the line of code. Somewhere, as I recall, I read that writing a = <EXP1> b = <EXP2> is preferable for reasons of clarity to a, b = <EXP1>, <EXP2> when the two assignments are unrelated. -- Jonathan _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
