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Manual Reference Pages  -  CLASS::MAKEMETHODS::EVALED::HASH (3)

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NAME

Class::MakeMethods::Evaled::Hash - Typical hash methods

CONTENTS

SYNOPSIS



  package MyObject;
  use Class::MakeMethods::Evaled::Hash (
    new => new,
    scalar => [ foo, bar ],
    array => my_list,
    hash => my_index,
  );
  ...
 
  # Constructor
  my $obj = MyObject->new( foo => Foozle );
 
  # Scalar Accessor
  print $obj->foo();
 
  $obj->bar(Barbados);
  print $obj->bar();
 
  # Array accessor
  $obj->my_list(0 => Foozle, 1 => Bang!);
  print $obj->my_list(1);
 
  # Hash accessor
  $obj->my_index(broccoli => Blah!, foo => Fiddle);
  print $obj->my_index(foo);



DESCRIPTION

The Evaled::Hash subclass of MakeMethods provides a simple constructor and accessors for blessed-hash object instances.

    Calling Conventions

When you use this package, the method names you provide as arguments cause subroutines to be generated and installed in your module.

See Calling Conventions in Class::MakeMethods::Standard for a summary, or USAGE in Class::MakeMethods for full details.

    Declaration Syntax

To declare methods, pass in pairs of a method-type name followed by one or more method names. Valid method-type names for this package are listed in METHOD GENERATOR TYPES.

See Declaration Syntax in Class::MakeMethods::Standard for more syntax information.

METHOD GENERATOR TYPES

    new - Constructor

For each method name passed, returns a subroutine with the following characteristics:
o If called as a class method, makes a new hash and blesses it into that class.
o If called on a hash-based instance, makes a copy of it and blesses the copy into the same class as the original instance.
o If passed a list of key-value pairs, appends them to the new hash. These arguments override any copied values, and later arguments with the same name will override earlier ones.
o Returns the new instance.
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Evaled::Hash (
    new => new,
  );
  ...
 
  # Bare constructor
  my $empty = MyObject->new();
 
  # Constructor with initial values
  my $obj = MyObject->new( foo => Foozle, bar => Barbados );
 
  # Copy with overriding value
  my $copy = $obj->new( bar => Bob );



    scalar - Instance Accessor

For each method name passed, uses a closure to generate a subroutine with the following characteristics:
o Must be called on a hash-based instance.
o Uses the method name as a hash key to access the related value for each instance.
o If called without any arguments returns the current value.
o If called with an argument, stores that as the value, and returns it,
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Evaled::Hash (
    scalar => foo,
  );
  ...
 
  # Store value
  $obj->foo(Foozle);
 
  # Retrieve value
  print $obj->foo;



    array - Instance Ref Accessor

For each method name passed, uses a closure to generate a subroutine with the following characteristics:
o Must be called on a hash-based instance.
o Uses the method name as a hash key to access the related value for each instance.
o The value for each instance will be a reference to an array (or undef).
o If called without any arguments, returns the current array-ref value (or undef).
o If called with one argument, uses that argument as an index to retrieve from the referenced array, and returns that value (or undef).
o If called with a list of index-value pairs, stores the value at the given index in the referenced array. If the instance’s value was previously undefined, a new array is autovivified. The current value in each position will be overwritten, and later arguments with the same index will override earlier ones. Returns the current array-ref value.
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Evaled::Hash (
    array => bar,
  );
  ...
 
  # Set values by position
  $obj->bar(0 => Foozle, 1 => Bang!);
 
  # Positions may be overwritten, and in any order
  $obj->bar(2 => And Mash, 1 => Blah!);
 
  # Retrieve value by position
  print $obj->bar(1);
   
  # Direct access to referenced array
  print scalar @{ $obj->bar() };
 
  # Reset the array contents to empty
  @{ $obj->bar() } = ();



    hash - Instance Ref Accessor

For each method name passed, uses a closure to generate a subroutine with the following characteristics:
o Must be called on a hash-based instance.
o Uses the method name as a hash key to access the related value for each instance.
o The value for each instance will be a reference to a hash (or undef).
o If called without any arguments, returns the current hash-ref value (or undef).
o If called with one argument, uses that argument as an index to retrieve from the referenced hash, and returns that value (or undef).
o If called with a list of key-value pairs, stores the value under the given key in the referenced hash. If the instance’s value was previously undefined, a new hash is autovivified. The current value under each key will be overwritten, and later arguments with the same key will override earlier ones. Returns the current hash-ref value.
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Evaled::Hash (
    hash => baz,
  );
  ...
 
  # Set values by key
  $obj->baz(foo => Foozle, bar => Bang!);
 
  # Values may be overwritten, and in any order
  $obj->baz(broccoli => Blah!, foo => Fiddle);
 
  # Retrieve value by key
  print $obj->baz(foo);
 
  # Direct access to referenced hash
  print keys %{ $obj->baz() };
 
  # Reset the hash contents to empty
  @{ $obj->baz() } = ();



SEE ALSO

See Class::MakeMethods for general information about this distribution.

See Class::MakeMethods::Evaled for more about this family of subclasses.

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perl v5.20.3 MAKEMETHODS::EVALED::HASH (3) 2004-09-06

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