On Sat, Oct 15, 2016 at 1:49 PM Steven D'Aprano <st...@pearwood.info> wrote: ...
> And the transformation of *t for the items of t (I don't care if it is a > real transformation in the implementation, or only a fictional > transformation) cannot work in a list comp. Let's make the number of > items of t explicit so we don't have to worry about variable item > counts: > > [*t for t in iterable] # t has three items > [a, b, c for (a, b, c) in iterable] > > > That's a syntax error. To avoid the syntax error, we need parentheses: > > [(a, b, c) for (a, b, c) in iterable] > > and that's a no-op. You are confusing here two distinct roles of the parenthesis: disambiguation as in "(1 + 2) * 2", and tuple construction as in (1, 2, 3). This overload is the reason that (1) is not a 1-tuple and we must write (1,). You may argue that this overloading causes confusion and make this construct hard to understand, but please be explicit about that; even if <1, 2,3 > was the syntax for tuples, the expansion was still [(a, b, c) for (a, b, c) in iterable] Since no tuple is constructed here. Elazar
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