[Python-ideas] Allow Context Managers to Support Suspended Execution

Rhodri James rhodri at kynesim.co.uk
Thu Nov 1 08:50:51 EDT 2018


On 01/11/2018 02:52, David Allemang wrote:
> I do not think there is currently a good way for Context Managers to
> support suspended execution, as in await or yield. Both of these
> instructions cause the interpreter to leave the with block, yet no
> indication of this (temporary) exit or subsequent re-entrance is given
> to the context manager. If the intent of a Context Manager is to say
> "no matter how this block is entered or exited, the context will be
> correctly maintained", then this needs to be possible.

I think you're going to have to justify this a bit more.  From my point 
of view, yielding does not leave the with block in any meaningful sense. 
  Indeed I'd be quite hacked off with a file context manager that was so 
inefficient as to close the file on yielding a line, only to have to 
re-open and seek when it got control back.


-- 
Rhodri James *-* Kynesim Ltd


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