Re: [Boost-users] Using Coroutines in the Visitor Pattern (use-case: BGL event visitor)

20 Jan 2016

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-----Original Message-----
From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf
Of
Nat Goodspeed
Sent: 19 January 2016 21:25
To: boost-users@lists.boost.org
Subject: Re: [Boost-users] Using Coroutines in the Visitor Pattern
(use-case: BGL
event visitor)
On Tue, Jan 19, 2016 at 6:02 AM, alex  wrote:
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I can see in the documentation that the constructor enters the
coroutine-
function, but it is not clear to me why. Would it not have been neater
if this was avoided?
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If the coroutine constructor didn't enter the coroutine-function, the
first invocation would have to be a special case.
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I expect the following in the evaluation of the while condition
1.The operator () will enter somefunc().
It is dawning on me now. At the first invocation operator() should enter
somefunc(), whereas at all subsequent invocations it has to re-enter
somefunc(). I suppose enter and re-enter are different operations, hence the
first invocation would be a special case. 

Thanks for indulging me.