[Python-Dev] PEP 492: No new syntax is required (original) (raw)

Mark Shannon mark at hotpy.org
Mon Apr 27 09:48:49 CEST 2015

On 27/04/15 00:13, Guido van Rossum wrote:

But new syntax is the whole point of the PEP. I want to be able to syntactically tell where the suspension points are in coroutines. Doesn't "yield from" already do that?

Currently this means looking for yield [from]; PEP 492 just adds looking for await and async [for|with]. Making await() a function defeats the purpose because now aliasing can hide its presence, and we're back in the land of gevent or stackless (where anything can potentially suspend the current task). I don't want to live in that land. I don't think I was clear enough. I said that "await" is a function, not that is should be disguised as one. Reading the code, "GetAwaitableIter" would be a better name for that element of the implementation. It is a straightforward non-blocking function.

On Sun, Apr 26, 2015 at 1:21 PM, Mark Shannon <mark at hotpy.org_ _<mailto:mark at hotpy.org>> wrote: Hi, I was looking at PEP 492 and it seems to me that no new syntax is required. Looking at the code, it does four things; all of which, or a functional equivalent, could be done with no new syntax. 1. Make a normal function into a generator or coroutine. This can be done with a decorator. 2. Support a parallel set of special methods starting with 'a' or 'async'. Why not just use the current set of special methods? 3. "await". "await" is an operator that takes one argument and produces a single result, without altering flow control and can thus be replaced by an function. 4. Asynchronous with statement. The PEP lists the equivalent as "with (yield from xxx)" which doesn't seem so bad. Please don't add unnecessary new syntax. Cheers, Mark. P.S. I'm not objecting to any of the other new features proposed, just the new syntax.

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