Perl 5 version 22.4 documentation

Tie::Handle

NAME

Tie::Handle - base class definitions for tied handles

SYNOPSIS

  1.     package NewHandle;
  2.     require Tie::Handle;
  4.     @ISA = qw(Tie::Handle);
  6.     sub READ { ... }		# Provide a needed method
  7.     sub TIEHANDLE { ... }	# Overrides inherited method
  10.     package main;
  12.     tie *FH, 'NewHandle';

DESCRIPTION

This module provides some skeletal methods for handle-tying classes. See perltie for a list of the functions required in tying a handle to a package. The basic Tie::Handle package provides a new method, as well as methods TIEHANDLE , PRINT , PRINTF and GETC .

For developers wishing to write their own tied-handle classes, the methods are summarized below. The perltie section not only documents these, but has sample code as well:

  • TIEHANDLE classname, LIST

    The method invoked by the command tie *glob, classname . Associates a new glob instance with the specified class. LIST would represent additional arguments (along the lines of AnyDBM_File and compatriots) needed to complete the association.

  • WRITE this, scalar, length, offset

    Write length bytes of data from scalar starting at offset.

  • PRINT this, LIST

    Print the values in LIST

  • PRINTF this, format, LIST

    Print the values in LIST using format

  • READ this, scalar, length, offset

    Read length bytes of data into scalar starting at offset.

  • READLINE this

    Read a single line

  • GETC this

    Get a single character

  • CLOSE this

    Close the handle

  • OPEN this, filename

    (Re-)open the handle

  • BINMODE this

    Specify content is binary

  • EOF this

    Test for end of file.

  • TELL this

    Return position in the file.

  • SEEK this, offset, whence

    Position the file.

    Test for end of file.

  • DESTROY this

    Free the storage associated with the tied handle referenced by this. This is rarely needed, as Perl manages its memory quite well. But the option exists, should a class wish to perform specific actions upon the destruction of an instance.

MORE INFORMATION

The perltie section contains an example of tying handles.

COMPATIBILITY

This version of Tie::Handle is neither related to nor compatible with the Tie::Handle (3.0) module available on CPAN. It was due to an accident that two modules with the same name appeared. The namespace clash has been cleared in favor of this module that comes with the perl core in September 2000 and accordingly the version number has been bumped up to 4.0.