Re^2: What is the scope of $

<tangent> How is @_ not global in scope? I mean, it gets implicitly localized on any subroutine call, but it's present by default and package independent:

use strict;
use warnings;

@_ = @ARGV;

package Foo;

print for @_;
@_ = qw(1 2 3 4 5);
{
    local @_ = reverse @_;
    print for @_;
}

package main;

print for @_;
[download]

</tangent>

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

Comment on Re^2: What is the scope of $_? Select or Download Code

Replies are listed 'Best First'.
Re^3: What is the scope of $_? by tobyink (Canon) on Nov 26, 2012 at 19:35 UTC
You are correct. I was under the impression that a reference to `@_` behaved differently than a reference to another localized array, once the localization went out of scope. But the following example appears to show they behave the same... `use strict; use Data::Dumper; our @X; my ($underscore, $scissors); @_ = (1..3); @X = (1..3); sub foo { local @X = (4..6); $underscore = \@_; $scissors = \@X; } foo(4..6); print Dumper($underscore, $scissors);` [download] So (like `$_`) `@_` is just a global array that gets localized by certain control structures. (In particular, `sub`.) `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^3: What is the scope of $_?
by tobyink (Canon) on Nov 26, 2012 at 19:35 UTC

You are correct. I was under the impression that a reference to @_ behaved differently than a reference to another localized array, once the localization went out of scope.

But the following example appears to show they behave the same...

use strict;
use Data::Dumper;

our @X;
my ($underscore, $scissors);

@_ = (1..3);
@X = (1..3);

sub foo {
    local @X = (4..6);
    $underscore = \@_;
    $scissors   = \@X;
}

foo(4..6);
print Dumper($underscore, $scissors);
[download]

So (like $_) @_ is just a global array that gets localized by certain control structures. (In particular, sub.)

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

[reply]
[d/l]
[select]