Further to soonix's answer, if you wish to not return anything from a function, use:

sub get_data {
   ...;
   return;   # undef in scalar context or the empty list in list conte
+xt
}
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or:

sub get_data {
   ...;
   return undef;   # undef in scalar context and a one-item list conta
+ining undef in list context
}
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Usually the former is preferred.

For object-oriented modules, if you don't have anything useful to return for a method, return $self is a good idea because it allows method calls to be easily chained, like:

  sub enable_warnings {
    my $self = shift;
    $self->{warnings} = 1;
    return $self;
  }
  sub enable_errors {
    my $self = shift;
    $self->{errors} = 1;
    return $self;
  }
  sub disable_warnings {
    my $self = shift;
    $self->{warnings} = 0;
    return $self;
  }
  sub disable_errors {
    my $self = shift;
    $self->{errors} = 0;
    return $self;
  }
  sub run_process {
    my $self = shift;
    ...;
    return $result;
  }

# Now instead of doing this:

$widget->enable_warnings;
$widget->enable_errors;
my $result = $widget->run_process;

# We can do this:

my $result = $widget->enable_warnings->enable_errors->run_process;
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A final note. Doing this:

sub bleh {
  return $result;
}
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Is actually very slightly slower than:

sub bleh {
  $result;
}
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So if you have a small function that gets called a lot and you want to optimize, removing return and just allowing the last value evaluated to fall through as the return value may give you a slight boost.