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Manual Reference Pages  -  CLASS::MAKEMETHODS::BASIC::ARRAY (3)

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NAME

Class::MakeMethods::Basic::Array - Basic array methods

CONTENTS

SYNOPSIS



  package MyObject;
  use Class::MakeMethods::Basic::Array (
    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 Basic::Array subclass of MakeMethods provides a basic constructor and accessors for blessed-array 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::Basic 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::Basic for more syntax information.

    About Positional Accessors

Each accessor method claims the next available spot in the array to store its value in.

The mapping between method names and array positions is stored in a hash named %FIELDS in the target package. When the first positional accessor is defined for a package, its %FIELDS are initialized by searching its inheritance tree.

<B>CautionB>: Subclassing packages that use positional accessors is somewhat fragile, since you may end up with two distinct methods assigned to the same position. Specific cases to avoid are:
o If you inherit from more than one class with positional accessors, the positions used by the two sets of methods will overlap.
o If your superclass adds additional positional accessors after you declare your first, they will overlap yours.

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 array and blesses it into that class.
o If called on an array-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 method-value pairs, calls each named method with the associated value as an argument.
o Returns the new instance.
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Basic::Array (
    new => new,
  );
  ...
 
  # Bare constructor
  my $empty = MyObject->new();
 
  # Constructor with initial sequence of method calls
  my $obj = MyObject->new( foo => Foozle, bar => Barbados );
 
  # Copy with overriding sequence of method calls
  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 an array-based instance.
o Determines the array position associated with the method name, and uses that as an index into each instance to access the related value.
o If called without any arguments returns the current value (or undef).
o If called with an argument, stores that as the value, and returns it,
Sample declaration and usage:



  package MyObject;
  use Class::MakeMethods::Basic::Array (
    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 an array-based instance.
o Determines the array position associated with the method name, and uses that as an index into each instance to access the related value.
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). If the single argument is an array ref, then a slice of the referenced array is returned.
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::Basic::Array (
    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);
 
  # Retrieve slice of values by position
  print join(, , $obj->bar( [0, 2] ) );
 
  # 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 an array-based instance.
o Determines the array position associated with the method name, and uses that as an index into each instance to access the related value.
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). If the single argument is an array ref, then a slice of the referenced hash is returned.
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::Basic::Array (
    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);
 
  # Retrieve slice of values by position
  print join(, , $obj->baz( [foo, bar] ) );
 
  # 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::Basic for more about this family of subclasses.

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perl v5.20.3 MAKEMETHODS::BASIC::ARRAY (3) 2004-09-06

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