NAME

Return::Value - Polymorphic Return Values

SYNOPSIS

  use Return::Value;
  
  sub send_over_network {
      my ($net, $send) = @_:
      if ( $net->transport( $send ) ) {
          return success;
      } else {
          return failure "Was not able to transport info.";
      }
  }
  
  my $result = $net->send_over_network(  "Data" );
  
  # boolean
  unless ( $result ) {
      # string
      print $result;
  }
  
  sub build_up_return {
      my $return = failure;
      
      if ( ! foo() ) {
          $return->string("Can't foo!");
          return $return;
      }
      
      if ( ! bar() ) {
          $return->string("Can't bar");
          $return->prop(failures => \@bars);
          return $return;
      }
      
      # we're okay if we made it this far.
      $return++;
      return $return; # success!
  }

DESCRIPTION

Polymorphic return values are really useful. Often, we just want to know if something worked or not. Other times, we'd like to know what the error text was. Still others, we may want to know what the error code was, and what the error properties were. We don't want to handle objects or data structures for every single return value, but we do want to check error conditions in our code because that's what good programmers do.

When functions are successful they may return true, or perhaps some useful data. In the quest to provide consistent return values, this gets confusing between complex, informational errors and successful return values.

This module provides these features with a simple API that should get you what you're looking for in each contex a return value is used in.

Functions

The functional interface is highly recommended for use within functions that are using Return::Values.

success

failure

Methods

The object API is useful in code that is catching Return::Value objects.

new

  my $return = Return::Value->new(
      bool   => 0,
      string => "YOU FAIL",
      prop   => {
          failed_objects => \@objects,
      },
  );

Creates a new Return::Value object. You can set the following options.

bool, the boolean representation of the result. Defaults to false.

errno, the error number. Defaults to 1 or 0 based on the value of bool.

string, the string representation of the result.

data, data associated with the result, usually for success.

prop, properties assigned to the result.

bool

  print "it worked" if $result->bool;

Returns a boolean describing the result as success or failure.

errno

  print "it worked" if $result->errno == 0;

Returns an errno for the result.

string

  print $result->string unless $result->bool;

Returns a boolean describing the result as success or failure.

data

  if ( $result->bool ) {
      my $data = $result->data;
      print foreach @{$data};
  }

Returns the data structure passed to it.

prop

  printf "%s: %s',
    $result->string, join ' ', @{$result->prop('strings')}
      unless $result->bool;

Returns the return value's properties. Accepts the name of a property retured, or returns the properties hash reference if given no name.

Overloading

Several operators are overloaded for Return::Value objects. They are listed here.

Stringify

  print "$result\n";

Stringifies to the string representation.

Boolean

  print $result unless $result;

Returns the bool representation.

Numeric

Also returns the bool value.