On 25 April 2018 at 03:01, Tim Peters <tim.pet...@gmail.com> wrote:
> assignment statement buried deep inside expressions. But in
> conventional use, "binding" is restricted to identifiers, which vastly
> simplifies the mental model for "the worst" that can happen.
[snip]
> But, in the absence of Guido chiming in, it's really up to you. A few
> people have expressed positive feelings about changing the name to
> "binding expressions", and none opposed it (that I saw), but the
> sample size is too small to claim that "proves" anything.
I go back and forth, as I suspect even if we call them "name binding
expressions" in the language reference (which I think would be a good
idea), they'll often be referred to colloquially as "assignment
expressions". That's probably OK though - list displays and dict
displays are regularly referred to as literals, and the meaning
remains clear, even though the use of literal is technically
inaccurate.
I also think it would be good for the PEP to spell out the following
semantic invariant for code running in a regular namespace:
_rhs = expr
assert (target := _rhs) is _rhs and target is _rhs
It's the restriction to single names as targets that makes it possible
to impose such a strong assertion about what the syntax means.
Cheers,
Nick.
--
Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia
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