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Postings from November 2019
On Thu, 28 Nov 2019 17:04:01 +0000
Dave Mitchell <davem@iabyn.com> wrote:
> =head2 :ro
...
I like this and its semantics, and I like the fact it isn't called
":const", thus saving that for perhaps an even-stronger version one day
that would guarantee no memory mutation (i.e. SV type upgrades), as may
be useful for shared memory or other ideas.
+1
> =head3 Reference Aliasing
>
> The first type, which I will call "reference aliasing", expects the
> argument to be a I<reference> to something, and the signature
> processing code first dereferences that argument (with dereference
> overloading honoured) and aliases the parameter to the resulting
> container - croaking if it's not a suitable reference. For example:
>
> sub foo(\$x, \@a, \%h, $other, $stuff) { ... }
>
> foo(\$X, [], \%H, 1, 2);
>
> Then within the body of foo(), $x is an alias for $X, @a for the
> anonymous array, and %h for %H. This type of aliasing is more useful
> for array and hash references, but scalars are supported for
> completeness. Note that @a and %h are *not* slurpy parameters; they
> consume a single argument, and more parameters can follow them.
An often-overlooked thought - what about ref-aliases to code blocks?
Now we have lexical subs, I wonder if we'd permit the following:
sub MY_map(\&body, @args) {
my @ret;
push @ret, body($_) for @args;
return @ret;
}
It seems a simple-enough addition of the idea to ref-alias a
`my sub foo` here.
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk | https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/