in reply to VB-ish behaviour byVar or byRef of objects in Perl

The same applies to non-objects as well. Everything is passed by reference in Perl. 

sub func { $_[0] = "bar"; }

my $s = "foo";
func($s);
print("$s\n");  # bar

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Re^2: VB-ish behaviour byVar or byRef of objects in Perl
by webfiend (Vicar) on Dec 11, 2007 at 20:54 UTC
    Everything is passed by reference in Perl.

    I know it's true, but the common ways to handle subroutine arguments sort of make it untrue.

    sub fiddle {
    my ($arg) = @_;
    $arg = "waffle";
}

sub faddle {
    my $arg = shift;
    $arg = "waffle";
}

sub muddle {
    $_[0] = "waffle";
}

my $value = "pancake";
print "$value\n"; # Prints "pancake"
fiddle($value);
print "$value\n"; # Prints "pancake"
faddle($value);
print "$value\n"; # Prints "pancake"
muddle($value);
print "$value\n"; # Prints "waffle"

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    Shifting and slicing @_ into subroutine lexicals will make copies (which only matters for simple non-reference values). I know, I know. This is obvious stuff I'm talking about. But when somebody hears that everything is passed by reference in Perl, they also need to hear that it's a behavior that often gets bypassed in idiomatic code.

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[d/l]

      Consider that it's because of the passed-by-aliasing behavior that those are the prevailing idoms . . . :)

      The cake is a lie.
      The cake is a lie.
      The cake is a lie.

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