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[Python-ideas] Syntax for key-value iteration over mappings
Sven R. Kunzesrkunze at mail.de
Mon Jul 27 18:02:18 CEST 2015
On 27.07.2015 17:45, Lennart Regebro wrote:> On Mon, Jul 27, 2015 at 5:30 PM, Sven R. Kunze <srkunze at mail.de> wrote:>> I cannot follow. There is nothing about 'await' that tells me it can only be>> used with coroutines. I need to memorize that fact, too.> No, because you get a syntax error when you use it incorrectly, so you> don't need to memorize that.> But here it works only with specific types.What's the difference?> Well, that is going to be the case now as well, you can't get away from that.Is it? I don't think so. There are many case where this is not the case.>>> Both are quite incomprehensible unless you know exactly what is going>>> on and that this is a shortcut for "fox x,y in foo.items():">> Same goes for .items(). It took some time to internalize this special case>> (at least from my perspective).> Sure, but now you have to learn what it is a special case of. All you> did was hide that it calls .items(), so the error message "foo does> not have an attribute 'items'" becomes harder to understand. You would> need to change that error to something else. And it really should be,> as you say, a SyntaxError, but it's a SyntaxError that can only be> raise in runtime. Which I think breaks most peoples understandning of> what a SyntaxError is...Nobody said it should be either. That is tiny detail and of course it should be a comprehensible error message.Btw. no newbie really knows what happens if they execute the default 'for' loop. You could say as well: "don't implement 'for' loops because they hide the fact of calling 'next'".
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