The implict reference is not a hard reference, as perlref speaks of, but an aliasing that occurs. For example:

sub x {
  $_[0] = "in x";
}
my $foo = "outside";
x($foo);
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sub x {
  my($foo) = @_;
  $foo = "in x";
}
my $foo = "outside";
x($foo);
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Read perldata, perlsyn, perlref and perlsub (if perlsub exists).

There are no pointers in perl, there are only scalar's hashes's and array's, and references. Some might say there are also lists, and they're right.

subroutines get arguments via the magical @_ variable, meaning every time you say Foo(1,2,3), inside of sub Foo, the @_ array will contain 1,2 and 3 as it's value.

That's pass-by-value.

my @Arra = ( 1, 2, 3, 4 );
PassByReference(\@Arra);
sub PassByReference {
     die "@_";
}
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use Data::Dumper;

DIE(1..10);
DIE(1,2,3,4,5,6,,8,9);
DIE( [ 1..10 ] );
DIE( { 1..10 } );
my @ARRAY = 1..10;
my %HASH = @ARRAY;

DIE( @ARRAY );
DIE( %HASH );


DIE( \@ARRAY );
DIE( \%HASH );


DIE( @ARRAY, \%HASH );

DIE( \@ARRAY, \%HASH );

DIE( \@ARRAY, %HASH );

DIE( \&DIE );
¨
DIE();


sub DIE { print Dumper(@_) };
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