On Tue, Aug 23, 2005 at 10:56:08 -0700, Larry Wall wrote: > We could probably extend "is cached" to attributes (and their implied > accessors) if lazy blocks aren't sufficient.
Hmm... With the whole distinction of &foo as a value and &foo() as a
application of the value, maybe we can sometimes assign a sub as an
rvalue by making a "weak" call.
sub lazy (Code &f) {
return &f.weak_call;
}
I like the relation to is cached, but I think it might be incorrect,
if the lazy block is reused.
BTW, I'm the "nothingmuch" who initially lobbied for lazy { }... =)
> : sub &infix:<||> ($left, $right is delayed) {
> : $left ?? $left :: ** $right; # can you steamroll a scalar?
> : }
>
> I'd really like to discourage people from writing thunks without curlies.
Then how do we define &infix:<||>'s prototype?
> I don't think steamrollering a scalar works--it would just take it
> as an operation on a list rather than on the elements of the list.
> You can't really delazify until you know what kind of a scalar you
> want, I suspect, because the lazy closure itself might need to know
> in what context to run. Otherwise you just have to return a proxy
> object that might turn into a string or number or int or whatever
> value is eventually wanted. Of course, presumably infix:<||> has
> that context already, so maybe we're looking for something like
>
> $right.want
This makes sense, but shuts off the 'want' behavior.
I think we should have an implicit $?CONTEXT object in each sub, and
then you can say to it
$?CONTEXT.unwrap($right);
or something along that metaphor.
This is also nice for things like
method moose (...) {
my Container $x = $?CONTEXT.eval( $?SELF.SUPER::moose ); #
maybe even a bit like Sub::Uplevel
...
# you can look inside $x now, but you can't "damage" it
# anymore
...
$x.unwrap; # this serves as context passthrough
}
> to force value-finding behavior iff it's called for. After all, you
> probably want it to stay lazy if you call it in undifferentiated scalar
> context:
>
> $x = $y || lazy { z() }
Yes, I didn't think about that... This is lazyness stacking though,
I think.
--
() Yuval Kogman <[EMAIL PROTECTED]> 0xEBD27418 perl hacker &
/\ kung foo master: /methinks long and hard, and runs away: neeyah!!!
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