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Re^3: [Perl 6] Any provision for a "dereferencing object"?

by blazar (Canon)
on May 28, 2007 at 21:47 UTC ( #617887=note: print w/replies, xml ) Need Help??


in reply to Re^2: [Perl 6] Any provision for a "dereferencing object"?
in thread [Perl 6] Any provision for a "dereferencing object"?

In perl5, what about something like...

my $a = []; $a->[1]{bar}{baz}[3] = 7; bless $a, "hrmph"; *hrmph::deref = sub { $_[0]->[1]{bar}{baz}[3] }; print "yeah: ", $a->deref, "\n";

Well, that's not quite the same thing, because you create a method for each "dereferencing chain". I was talking about putting it e.g. in some scalar or in an aggregate. But now that you got me thinking, this is certainly possible and even easier than what you wrote:

my $x = []; $x->[1]{bar}{baz}[3] = 7; bless $x, "whatever"; my $deref = sub { $_[0]->[1]{bar}{baz}[3] }; print "yeah: ", $x->$deref, "\n";

What's even more interesting is that the variable appearently doesn't need to be blessed at all, which I wouldn't have known nor suspected without trying. In fact the following works just the same too:

my $x = []; $x->[1]{bar}{baz}[3] = 7; # bless $x, "whatever"; my $deref = sub { $_[0]->[1]{bar}{baz}[3] }; print "yeah: ", $x->$deref, "\n";
It's maybe not the clearest or most maintainable thing in the whole wide world, but it's not "impossible."

Well, what I wrote -literally- is still impossible: that is precisely to have a "dereferencing chain" as a self sustained "single entity", existing in and of itself without a reference to be applied to. In fact here we have a cheap workaround that is perfectly equivalent. Yet it's not, from the "philosophical" POV, exactly the same thing.

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