Question

Would somebody be so pleasant to explain why does the next thing happen? Here is the code:

#!/usr/bin/perl
use v5.14;
use warnings;

my @arr = (1, 2, 3);

sub func
{
    return @arr;
}

push(&func(), 4);

say @arr;

When I try to run it, the output is Not an ARRAY reference at ....

I suppose that this is because &func() evaluates not to the @arr, but to a plain list 1, 2, 3 and 1 is treated as ARRAY argument to the push. Can somebody explain why does this happen, cause in the push documentation I found nothing related to this.

Thanks in advance.

Answer 1

It’s impossible for a sub to return an array. You are returning the result of evaluating the array in list context, which is to say you are returning a list of its content. Obviously, that’s not what you want.

push will now accept a reference to an array, so you could use

sub func {
   return \@arr;
}

push(func(), 4);

Note that push required an array literal until recently, so must use the following if you want backwards compatibility:

sub func {
   return \@arr;
}

push(@{ func() }, 4);

---

PS — Note that I removed the &. Why are you telling Perl to ignore the prototype of a sub that has no prototype?