


MakeMethods::StUserrContributed)PMakeMethods::Standard::Array(3p)


NAME
       Class::MakeMethods::Standard::Array - Methods for Array objects

SYNOPSIS
         package MyObject;
         use Class::MakeMethods::Standard::Array (
           new => 'new',
           scalar => [ 'foo', 'bar' ],
           array => 'my_list',
           hash => 'my_index',
         );
         ...

         my $obj = MyObject->new( foo => 'Foozle' );
         print $obj->foo();

         $obj->bar('Barbados');
         print $obj->bar();

         $obj->my_list(0 => 'Foozle', 1 => 'Bang!');
         print $obj->my_list(1);

         $obj->my_index('broccoli' => 'Blah!', 'foo' => 'Fiddle');
         print $obj->my_index('foo');

DESCRIPTION
       The Standard::Array suclass 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::Standard for more
       information.

   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 and "Parameter
       Syntax" in Class::MakeMethods::Standard for more information.

   Positional Accessors and %FIELDS
       Each accessor method is assigned the next available array index at
       which to store its value.

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



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       Warning: 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   Has a reference to a sample item to copy. This defaults to a
           reference to an empty array, but you may override this with the
           "'defaults' =" array_ref> method parameter.

       o   If called as a class method, makes a new array containing values
           from the sample item, 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::Standard::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



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           uses that as an index into each instance to access the related
           value. This defaults to the next available slot in %FIELDS, but you
           may override this with the "'array_index' =" number> method
           parameter, or by pre-filling the contents of %FIELDS.

       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::Standard::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. This defaults to the next available slot in %FIELDS, but you
           may override this with the "'array_index' =" number> method
           parameter, or by pre-filling the contents of %FIELDS.

       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 a single non-ref argument, uses that argument as an
           index to retrieve from the referenced array, and returns that value
           (or undef).

       o   If called with a single array ref argument, uses that list to
           return a slice of the referenced array.

       o   If called with a list of argument pairs, each with a non-ref index
           and an associated value, 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



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           will be overwritten, and later arguments with the same index will
           override earlier ones. Returns the current array-ref value.

       o   If called with a list of argument pairs, each with the first item
           being a reference to an array of up to two numbers, loops over each
           pair and uses those numbers to splice the value array.

           The first controlling number is the position at which the splice
           will begin. Zero will start before the first item in the list.
           Negative numbers count backwards from the end of the array.

           The second number is the number of items to be removed from the
           list. If it is omitted, or undefined, or zero, no items are
           removed. If it is a positive integer, that many items will be
           returned.

           If both numbers are omitted, or are both undefined, they default to
           containing the entire value array.

           If the second argument is undef, no values will be inserted; if it
           is a non-reference value, that one value will be inserted; if it is
           an array-ref, its values will be copied.

           The method returns the items that removed from the array, if any.

       Sample declaration and usage:

         package MyObject;
         use Class::MakeMethods::Standard::Array (
           array => 'bar',
         );
         ...

         # Clear and set contents of list
         print $obj->bar([ 'Spume', 'Frost' ] );

         # 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() };

       There are also calling conventions for slice and splice operations:

         # Retrieve slice of values by position
         print join(', ', $obj->bar( undef, [0, 2] ) );

         # Insert an item at position in the array



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         $obj->bar([3], 'Potatoes' );

         # Remove 1 item from position 3 in the array
         $obj->bar([3, 1], undef );

         # Set a new value at position 2, and return the old value
         print $obj->bar([2, 1], 'Froth' );

   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. This defaults to the next available slot in %FIELDS, but you
           may override this with the "'array_index' =" number> method
           parameter, or by pre-filling the contents of %FIELDS.

       o   The value for each instance will be a reference to a hash (or
           undef).

       o   If called without any arguments, returns the contents of the hash
           in list context, or a hash reference in scalar context (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 contents of the
           hash in list context, or a hash reference in scalar context.

       Sample declaration and usage:

         package MyObject;
         use Class::MakeMethods::Standard::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');



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         # Retrive 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() } = ();

   object - 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. This defaults to the next available slot in %FIELDS, but you
           may override this with the "'array_index' =" number> method
           parameter, or by pre-filling the contents of %FIELDS.

       o   The value for each instance will be a reference to an object (or
           undef).

       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::Standard::Hash (
           object => 'foo',
         );
         ...

         # Store value
         $obj->foo( Foozle->new() );

         # Retrieve value
         print $obj->foo;

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

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

       See Class::MakeMethods::Standard::Hash for equivalent functionality
       based on blessed hashes. If your module will be extensively subclassed,
       consider switching to Standard::Hash to avoid the subclassing concerns
       described above.



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