[Python-ideas] Delayed Execution via Keyword

[Joseph Hackman]

Abe-

You are correct. However I think it may still be salvageable.

In your code example, you could be either making a dict with a key of 1, or a set of a delayed object. But there's no reason to build a set of a delayed object because hashing it would immediately un-delay. 

Similarly, I am not sure delayed should be allowed inside of function headers. 

So we could say that dictionary keys and sets shouldn't be allowed to use the delayed keyword. Same with function headers. Are there any other collisions?

-Joseph

On Feb 17, 2017, at 3:41 PM, Abe Dillon <abedillon at gmail.com> wrote:

>> Couldn't the same thing be true of delayed if it is always followed by a colon?
> 
> No. Because there are other reasons you'd follow the variable `delayed` with a colon:
> 
> >>> delayed = 1
> >>> d = {delayed: "oops!"}
> 
> My earlier proposal (using unpacking syntax) doesn't work for the same reason.  
> 
>> On Fri, Feb 17, 2017 at 2:31 PM, Joseph Hackman <josephhackman at gmail.com> wrote:
>> Couldn't the same thing be true of delayed if it is always followed by a colon?
>> 
>> I.e. 
>> delayed=1
>> x= delayed: slow_function()
>> print(delayed) # prints 1
>> 
>> -Joseph
>> 
>>> On Feb 17, 2017, at 2:39 PM, Mark E. Haase <mehaase at gmail.com> wrote:
>>> 
>>>> On Fri, Feb 17, 2017 at 1:55 PM, Joshua Morton <joshua.morton13 at gmail.com> wrote:
>>>> but I'm wondering how common async and await were when that was proposed and accepted?
>>> 
>>> 
>>> Actually, "async" and "await" are backwards compatible due to a clever tokenizer hack. The "async" keyword may only appear in a few places (e.g. async def), and it is treated as a name anywhere else.The "await" keyword may only appear inside an "async def" and is treated as a name everywhere else. Therefore...
>>> 
>>>     >>> async = 1
>>>     >>> await = 1
>>> 
>>> ...these are both valid in Python 3.5. This example is helpful when proposing new keywords.
>>> 
>>> More info: https://www.python.org/dev/peps/pep-0492/#transition-plan
>>> 
>>> 
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