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Postings from June 2013
On Mon, Jun 10, 2013 at 2:27 PM, demerphq <demerphq@gmail.com> wrote:
> On 3 June 2013 14:06, Ruslan Zakirov <ruz@bestpractical.com> wrote:
> > HI,
> >
> > I've updated patches that add key/value hash slices to perl syntax:
> >
> > my %sub_hash = %hash{qw(some keys go here)};
>
> Sounds cool.
>
> However note that it is legal, but deprecated to write this:
>
> $ perl -le'my $hash={foo=>"bar"}; print %$hash->{foo};'
> Using a hash as a reference is deprecated at -e line 1.
> bar
>
> How does your patch impact this behavior?
>
I was only concentrated on making the following work as key/value slices:
%{ $hash_ref }{qw(.....)}
I should write tests for this.
Syntax you mentioned is grey area and I will do whatever people decide, but
I think it should be parsed in very same way as the following code:
$ perl -le'my $hash={foo=>"bar"}; print @$hash->{foo};'
Correct way to write what you want is %$hash_ref{'foo', 'bar'} and it
should work already. Note for myself to write tests for the case.
I have "quest" [1] on subject of working with references, but it's
completly different story. My goal at this moment is to make key/value
slices fully aligned with how existing slice ops behave.
[1] http://questhub.io/perl/quest/512f884520d03fb31200003b
> Also what happens if I do:
>
> my $sub_hash= %hash{thing};
>
> does $sub_hash end up with the value 2 if "thing" existed, and with
> the value 0 if it didn't?
>
It end ups with value, not 2 or 0 and produce a warning (%hash{'thing'} is
better written as $hash{'thing'}). As aslice and hslice, kvhslice returns
list, so last element is assigned to $sub_hash which is value. I hate this
"list" thing, but I'm for consistency.
If someone does this should it warn?
>
It does already. Should it warn in array context? It's still open question.
Warns in the same style as aslice or hslice, so can be workarounded.
>
> > This feature was discussed [1] back in Feb with Brad Gilbert. We agreed
> that
> > for consistency this should work with arrays too as index/value array
> slice.
> > I've added array functionality. Also, wrote a few basic tests.
> >
> > Main question is whether should I continue or stop right there as it
> never
> > will be in the core?
> >
> > A quick review of the code [2] would be helpful too.
> >
> > [1]
> http://www.nntp.perl.org/group/perl.perl5.porters/2013/02/msg199485.html
> > [2] https://github.com/ruz/perl5/tree/ruz/kvhslice-op
>
> Thanks for working on this Ruslan!
>
> Yves
>
>
> --
> perl -Mre=debug -e "/just|another|perl|hacker/"
>
--
Best regards, Ruslan.
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