Looking at the grammar -- the only downside of the current approach is that
you can't do 'await await fut'. I still think that it reads better with
parens. If we put 'await' to 'factor' terminal we would allow
await -fut # await (-fut)
I think I something like
power: atom_expr ['**' factor]
atom_expr: [AWAIT] atom_expr | atom_trailer
atom_trailer: atom trailer*
will fix 'await await' situation, but does it really need to be fixed?
Yury
On 2015年04月27日 9:44 AM, Yury Selivanov wrote:
Hi Greg,
I don't want this: "await a() * b()" to be parsed, it's not meaningful.
Likely you'll see "await await a()" only once in your life, so I'm
fine to use parens for it (moreover, I think it reads better with parens)
Yury
On 2015年04月27日 8:52 AM, Greg Ewing wrote:
Yury Selivanov wrote:
I've done some experiments with grammar, and it looks like
we indeed can parse await quite differently from yield. Three
different options:
You don't seem to have tried what I suggested, which is
to make 'await' a unary operator with the same precedence
as '-', i.e. replace
factor: ('+'|'-'|'~') factor | power
with
factor: ('+'|'-'|'~'|'await') factor | power
That would allow
await a()
res = await a() + await b()
res = await await a()
if await a(): pass
return await a()
print(await a())
func(arg=await a())
await a() * b()
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