[issue34380] Relax Restrictions on await?

[Steven Silvester]

Steven Silvester  added the comment:

Thanks for your consideration and for implementing the original feature!

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[issue34380] Relax Restrictions on await?

[Yury Selivanov]

Yury Selivanov  added the comment:

This isn't something we want to do in Python.  We have a dynamic but strict 
type system. 1 + '1' is an error in Python, but works just fine in JavaScript.  
Likewise, in 'await foo' foo is expected to be an awaitable in Python and not 
anything else.  This has been discussed multiple times during PEP 492 approval 
process.

I've been beaten myself by lose semantics of await in JS by awaiting a function 
that returned null—a simple bug that turned out to be a nightmare to identify 
in a complex system.

So unfortunately I have to close this one as "won't fix", sorry. Thank you for 
suggesting the idea though.

--
resolution:  -> rejected
stage:  -> resolved
status: open -> closed
type:  -> behavior

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[issue34380] Relax Restrictions on await?

[Steven Silvester]

New submission from Steven Silvester :

When writing an `async` function, we often want to `await` a method call that 
may or may not be `async`.  For instance, it may be synchronous in the base 
class, but asynchronous in the subclass on the instance we have been given.  It 
would be nice for `await foo` to be a no-op if `foo` does not have an 
`__await__` method.  For instance, the following works in EMCAScript 2017:  
`async function foo () { let bar = await 1; console.log(bar); }`.  As a 
workaround, we have been using `await force_async(foo.bar)`, where 
`force_async` is the following:

```python
async def force_async(obj):
"""Force an object to be asynchronous"""
if hasattr(obj, '__await__'):
return await obj
async def inner():
return obj
return await inner()
```

This functionality is roughly equivalent to `gen.maybe_future` for coroutines, 
that is now deprecated in Tornado.  cf 
http://www.tornadoweb.org/en/stable/gen.html#tornado.gen.maybe_future

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components: asyncio
messages: 323410
nosy: Steven Silvester, asvetlov, yselivanov
priority: normal
severity: normal
status: open
title: Relax Restrictions on await?
versions: Python 3.8

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