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Re: Perl_peep (was Re: Perl_linklist)

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Rafael Garcia-Suarez
December 3, 2008 13:57
Re: Perl_peep (was Re: Perl_linklist)
Message ID:
2008/12/3 Matt S Trout <>:
> On Wed, Nov 26, 2008 at 09:30:43PM +0000, Nicholas Clark wrote:
>> On Wed, Nov 26, 2008 at 04:10:58PM +0000, Nicholas Clark wrote:
>> > On Wed, Nov 26, 2008 at 04:36:34PM +0100, Rafael Garcia-Suarez wrote:
>> > > 2008/11/26 Nicholas Clark <>:
>> > > > Do we want to make that policy decision? That optree construction is private.
>> > >
>> > > If it's not private, it's public somehow. I merely want to assert that
>> > > we don't support the internal API that is used to construct and
>> > > optimise optrees. Perl_peep() is not public either, for example. Those
>> > > are functions that do more than optree inspection.
>> >
>> > To my mind the most logical way to assert that we don't support something is
>> > to make it static whenever we can. So I made the appended change.
>> > (And then went looking for other non-public non-static functions that the
>> > core does not need outside the file of their definition)
>> To be consistent that would mean that Perl_peep() becomes static S_peep().
>> Which, at least, will cause optimizer.xs to fail to link.
>> (Although, curiously, not B::Generate)
>> If we go all the way down the road of "the API used to construct and optimise
>> optrees is internal" then we preclude certain potentially useful modules
>> appearing on CPAN.
>> So should we provide some level of API? If so, what?
> I'd like to be able to do much of what the compiler is able to currently.
> I'm also aware that's a lot of API to maintain.
> But at the very least I think we should consider current CPAN usages to be
> a baseline - "some sort of op creation callback" plus "a way to construct your
> own optree (fragments) and turn them into something runnable" plus "a way to
> run an optree fragment" - though I wouldn't horribly mind building a proper
> CV and executing it normally, I worry about the performance for that when
> trying to do clever things like building macros (also when writing keywords
> that take an expr ala map/grep, rather than just ones that take a sub).

That's true. An optree constructed by hand is made "runnable" by
linklist. Actually it's a good way to describe what linklist does.
That would be a good argument to make linklist public.

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