[perl #126424] Iterators that don't use pull-one, lose containers
On Wed Oct 21 15:40:57 2015, elizabeth wrote:
> # this internally uses .push-at-least
> $ 6 'my $l = gather { take-rw my $ = 1 }; $l.AT-POS(0) = 42'
> Cannot modify an immutable Int
> in block at -e:1
>
> # this internally uses .pull-one
> $ 6 'my $l = gather { take-rw my $ = 1 }; for @$l { $_ = 42 }; dd
> $l.AT-POS(0)'
> Int $var = 42
>
> The former follows List!AT-POS-SLOWPATH, which in turn calls .push-at-
> least. The latter does a .pull-one.
>
>
> There were some “is raw” missing, but not on the AT-POS’s that were
> encountered in this example.
>
> Also considered that we would need to have a Mu on the $pulled in
> Iterator.push-at-least.
>
>
> I also checked pushing to IterationBuffer:
>
> $ 6 'my $b = IterationBuffer.new; my $a = 42; $b.push($a); dd $b[0] =
> 666'
> Int $var = 666
>
> So, I’m not sure anymore what TF is going on :-(
>
Tracked it down. It wasn't actually anything to do with pull-one vs.
push-at-least in the end, but instead that AT-POS in Seq was lacking "is raw".
Added that, it things worked. Test coverage in S04-statements/gather.t.
[perl #126424] Iterators that don't use pull-one, lose containers
# New Ticket Created by Elizabeth Mattijsen
# Please include the string: [perl #126424]
# in the subject line of all future correspondence about this issue.
# https://rt.perl.org/Ticket/Display.html?id=126424 >
# this internally uses .push-at-least
$ 6 'my $l = gather { take-rw my $ = 1 }; $l.AT-POS(0) = 42'
Cannot modify an immutable Int
in block at -e:1
# this internally uses .pull-one
$ 6 'my $l = gather { take-rw my $ = 1 }; for @$l { $_ = 42 }; dd $l.AT-POS(0)'
Int $var = 42
The former follows List!AT-POS-SLOWPATH, which in turn calls .push-at-least.
The latter does a .pull-one.
There were some “is raw” missing, but not on the AT-POS’s that were encountered
in this example.
Also considered that we would need to have a Mu on the $pulled in
Iterator.push-at-least.
I also checked pushing to IterationBuffer:
$ 6 'my $b = IterationBuffer.new; my $a = 42; $b.push($a); dd $b[0] = 666'
Int $var = 666
So, I’m not sure anymore what TF is going on :-(
Liz
