[erlang-questions] [RFC] smarter receive
Fri Nov 10 16:06:38 CET 2006
On Friday 10 November 2006 04:14, Jay Nelson wrote:
> I wasn't sure that this message was about "proposal to enhance message
> because the thread name changed. You quoted a book I never mentioned and
> then had code that looked very similar to mine. I assume this is
> somehow related
> and will try to answer.
Yes, it is another proposal.
> > Why not remember this position for next time?
> > Since the test is constant none of the already scanned messages will
> > next time either!
> This only helps in the case of constant data. If there is a variable
> that could change because it is a loop argument or the result of
> another receive, then you must resort back to the full scanning method.
> This would solve the problem in some cases, but not all, while making
> the implementation more complex.
I know - I wrote that too :-)
OK, lets try to simplify as much as possible, what is the most common case?
I would guess it is: Tuple with first element a constant atom.
(It would be quite easy to rewrite code in this way... easier than rewriting
code to match your proposal anyway)
Each receive statement needs to save a pointer to how far in the queue
it has searched or each match could cache the same info. Any receive with
a match all would not need to save anything.
>> - - -
> You don't want to change the fundamental semantics of receive in that
> messages are scanned from earliest to latest, and that the order of pattern
> clauses in a receive statement matters
I never intended to change the semantics. Implementation could change...
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