Class::MakeMethods::Standard::Array - Methods for Array objects
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');
The Standard::Array suclass of MakeMethods provides a basic constructor and
accessors for blessed-array object instances.
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.
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.
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.
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:
- •
- If you inherit from more than one class with positional
accessors, the positions used by the two sets of methods will
overlap.
- •
- If your superclass adds additional positional accessors
after you declare your first, they will overlap yours.
For each method name passed, returns a subroutine with the following
characteristics:
- •
- 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.
- •
- If called as a class method, makes a new array containing
values from the sample item, and blesses it into that class.
- •
- If called on an array-based instance, makes a copy of it
and blesses the copy into the same class as the original instance.
- •
- If passed a list of method-value pairs, calls each named
method with the associated value as an argument.
- •
- 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' );
For each method name passed, uses a closure to generate a subroutine with the
following characteristics:
- •
- Must be called on an array-based instance.
- •
- 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.
- •
- If called without any arguments returns the current value
(or undef).
- •
- 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;
For each method name passed, uses a closure to generate a subroutine with the
following characteristics:
- •
- Must be called on an array-based instance.
- •
- 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.
- •
- The value for each instance will be a reference to an array
(or undef).
- •
- If called without any arguments, returns the current
array-ref value (or undef).
- •
- 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).
- •
- If called with a single array ref argument, uses that list
to return a slice of the referenced array.
- •
- 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 will be
overwritten, and later arguments with the same index will override earlier
ones. Returns the current array-ref value.
- •
- 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
$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' );
For each method name passed, uses a closure to generate a subroutine with the
following characteristics:
- •
- Must be called on an array-based instance.
- •
- 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.
- •
- The value for each instance will be a reference to a hash
(or undef).
- •
- If called without any arguments, returns the contents of
the hash in list context, or a hash reference in scalar context (or
undef).
- •
- 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.
- •
- 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');
# 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() } = ();
For each method name passed, uses a closure to generate a subroutine with the
following characteristics:
- •
- Must be called on an array-based instance.
- •
- 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.
- •
- The value for each instance will be a reference to an
object (or undef).
- •
- If called without any arguments returns the current
value.
- •
- 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 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.