Hi,
Ted Zlatanov wrote:
> I have a Perl 5 module called Every which provides, simply,
>
> every(5); # true on invocation 5, 10, etc.
> every(seconds => 5); # true at 5, 10, etc. seconds
>
> It's really nice in endless loops, logging, etc. I'd like to translate
> it to Perl 6 (using Rakudo specifically).
>
> Its current implementation requires Devel::Opcode because it needs to
> know what location is getting called again and again.
>
> Generally for Perl 6, is there a simple way to make Every obsolete by
> using built-ins?
State variables will probably make that a lot easier. Something like
(do { state $x; $x++}) %% 5
> I'd love that but haven't seen anything in the
> language that would help. I want to avoid closures, they are expensive
> (the current implementation uses one hash key per location). Maybe I
> could use a continuation (I don't know the syntax for that)?
>
> Specifically for Rakudo, if I have to implement it, can I avoid
> Devel::Opcode? Are continuations expensive?
Currently there is no Devel::Opcode in Rakudo (and I doubt that it will
work when being called through Blizkost), and everything is expensive :/
Once macros and 'state' are implemented, I think it will be easy to turn
every(5)
into
(do { state $x; $x++}) %% 5
Until then the best you can do for now is probably to use
callframe(1).file and .line to fingerprint the source location. You'll
only get line-level resolution, but that should be enough for a start.
Cheers,
Moritz
