On Tue, Feb 21, 2017 at 12:45 PM, Ian Lance Taylor <[email protected]> wrote:
> On Tue, Feb 21, 2017 at 11:15 AM, Thomas Bushnell, BSG
> <[email protected]> wrote:
>> On Mon, Feb 20, 2017 at 11:42 AM Ian Lance Taylor <[email protected]> wrote:
>>>
>>> On Sun, Feb 19, 2017 at 2:57 PM,  <[email protected]> wrote:
>>> > Thanks, I see you build it up with decorators on a standard prototype.
>>> > For example: https://play.golang.org/p/PJy5lE9QqF
>>> >
>>> > So context.Done is a convenience function for those that require it?
>>> > Otherwise a context will expire after it leaves scope, so Done does not
>>> > need
>>> > to be called?
>>>
>>> Cancelling the context just marks the context as cancelled.  It does
>>> not actually stop any goroutines using the context.  Those goroutines
>>> must themselves periodically check the context to see whether it has
>>> been cancelled, and, if so, stop working.  They do that by calling
>>> either the Done or Err method; it's much more common to call the Done
>>> method (and check whether the channel is closed).
>>
>>
>> Calling the Err() method to see if the context has been cancelled is
>> incorrect.
>
> ...
>
>> "Err's return value is unspecified before Done is closed."
>
> Hmmm, that text is not in the version of the context package included
> in the Go standard library.  Perhaps it should be.

Sent https://golang.org/cl/37375 .

Ian

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