Tie::Array - base class for tied arrays
- package Tie::NewArray;
- use Tie::Array;
- @ISA = ('Tie::Array');
- # mandatory methods
- sub TIEARRAY { ... }
- sub FETCH { ... }
- sub FETCHSIZE { ... }
- sub STORE { ... } # mandatory if elements writeable
- sub STORESIZE { ... } # mandatory if elements can be added/deleted
- sub EXISTS { ... } # mandatory if exists() expected to work
- sub DELETE { ... } # mandatory if delete() expected to work
- # optional methods - for efficiency
- sub CLEAR { ... }
- sub PUSH { ... }
- sub POP { ... }
- sub SHIFT { ... }
- sub UNSHIFT { ... }
- sub SPLICE { ... }
- sub EXTEND { ... }
- sub DESTROY { ... }
- package Tie::NewStdArray;
- use Tie::Array;
- @ISA = ('Tie::StdArray');
- # all methods provided by default
- package main;
- $object = tie @somearray,'Tie::NewArray';
- $object = tie @somearray,'Tie::StdArray';
- $object = tie @somearray,'Tie::NewStdArray';
This module provides methods for array-tying classes. See
perltie for a list of the functions required in order to tie an array
to a package. The basic Tie::Array package provides stub DESTROY
,
and EXTEND
methods that do nothing, stub DELETE
and EXISTS
methods that croak() if the delete() or exists() builtins are ever called
on the tied array, and implementations of PUSH
, POP
, SHIFT
,
UNSHIFT
, SPLICE
and CLEAR
in terms of basic FETCH
, STORE
,
FETCHSIZE
, STORESIZE
.
The Tie::StdArray package provides efficient methods required for tied arrays which are implemented as blessed references to an "inner" perl array. It inherits from Tie::Array, and should cause tied arrays to behave exactly like standard arrays, allowing for selective overloading of methods.
For developers wishing to write their own tied arrays, the required methods are briefly defined below. See the perltie section for more detailed descriptive, as well as example code:
The class method is invoked by the command tie @array, classname
. Associates
an array instance with the specified class. LIST
would represent
additional arguments (along the lines of AnyDBM_File and compatriots) needed
to complete the association. The method should return an object of a class which
provides the methods below.
Store datum value into index for the tied array associated with
object this. If this makes the array larger then
class's mapping of undef should be returned for new positions.
Retrieve the datum in index for the tied array associated with object this.
Returns the total number of items in the tied array associated with
object this. (Equivalent to scalar(@array)).
Sets the total number of items in the tied array associated with
object this to be count. If this makes the array larger then
class's mapping of undef should be returned for new positions.
If the array becomes smaller then entries beyond count should be
deleted.
Informative call that array is likely to grow to have count entries. Can be used to optimize allocation. This method need do nothing.
Verify that the element at index key exists in the tied array this.
The Tie::Array implementation is a stub that simply croaks.
Delete the element at index key from the tied array this.
The Tie::Array implementation is a stub that simply croaks.
Clear (remove, delete, ...) all values from the tied array associated with object this.
Normal object destructor method.
Append elements of LIST to the array.
Remove last element of the array and return it.
Remove the first element of the array (shifting other elements down) and return it.
Insert LIST elements at the beginning of the array, moving existing elements up to make room.
Perform the equivalent of splice on the array.
offset is optional and defaults to zero, negative values count back from the end of the array.
length is optional and defaults to rest of the array.
LIST may be empty.
Returns a list of the original length elements at offset.
There is no support at present for tied @ISA. There is a potential conflict between magic entries needed to notice setting of @ISA, and those needed to implement 'tie'.
Very little consideration has been given to the behaviour of tied arrays
when $[
is not default value of zero.
Nick Ing-Simmons <nik@tiuk.ti.com>