Re: technique of push

Operators define their own parsing rules. Some of these can be approximated using prototypes.

sub my_push(\@@) {
    my $ref = shift;
    push @$ref, @_;
    return 0+@$ref;
}

my @a = (1..4);
my_push(@a, 5);
print "@a\n";  # 1 2 3 4 5
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Comment on Re: technique of push Download Code

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Re^2: technique of push by saranperl (Initiate) on Sep 02, 2009 at 07:14 UTC
could you explain what is "my_push(\@@)" and "return 0+ @$ref"	[reply]
Re^3: technique of push by ikegami (Patriarch) on Sep 02, 2009 at 07:22 UTC
I said it was a prototype. You could have searched the docs for "prototype" :-( They're documented in perlsub. As for `0+@$ref`, it adds zero to the value to which `@$ref` evaluates. Keep in mind that the addition operator imposes a scalar context on its operands. perldata says "If you evaluate an array in scalar context, it returns the length of the array." Zero plus the length of the array is the length of the array. Since `push` returns the length of the resulting array, I made `my_push` return the same thing. (Without the `0+`, `@$ref` would be evaluated in the same context as the `my_push` call, and could result in the wrong value being returned.)	[reply] [d/l] [select]