phpman > perldoc > IO::Wrap

NAME
    IO::Wrap - wrap raw filehandles in IO::Handle interface

SYNOPSIS
       use IO::Wrap;

       ### Do stuff with any kind of filehandle (including a bare globref), or
       ### any kind of blessed object that responds to a print() message.
       ###
       sub do_stuff {
           my $fh = shift;

           ### At this point, we have no idea what the user gave us...
           ### a globref? a FileHandle? a scalar filehandle name?

           $fh = wraphandle($fh);

           ### At this point, we know we have an IO::Handle-like object!

           $fh->print("Hey there!");
           ...
       }

DESCRIPTION
    Let's say you want to write some code which does I/O, but you don't want to force the caller to
    provide you with a FileHandle or IO::Handle object. You want them to be able to say:

        do_stuff(\*STDOUT);
        do_stuff('STDERR');
        do_stuff($some_FileHandle_object);
        do_stuff($some_IO_Handle_object);

    And even:

        do_stuff($any_object_with_a_print_method);

    Sure, one way to do it is to force the caller to use tiehandle(). But that puts the burden on
    them. Another way to do it is to use IO::Wrap, which provides you with the following functions:

    wraphandle SCALAR
        This function will take a single argument, and "wrap" it based on what it seems to be...

        *   A raw scalar filehandle name, like "STDOUT" or "Class::HANDLE". In this case, the
            filehandle name is wrapped in an IO::Wrap object, which is returned.

        *   A raw filehandle glob, like "\*STDOUT". In this case, the filehandle glob is wrapped in
            an IO::Wrap object, which is returned.

        *   A blessed FileHandle object. In this case, the FileHandle is wrapped in an IO::Wrap
            object if and only if your FileHandle class does not support the "read()" method.

        *   Any other kind of blessed object, which is assumed to be already conformant to the
            IO::Handle interface. In this case, you just get back that object.

    If you get back an IO::Wrap object, it will obey a basic subset of the IO:: interface. That is,
    the following methods (note: I said *methods*, not named operators) should work on the thing you
    get back:

        close
        getline
        getlines
        print ARGS...
        read BUFFER,NBYTES
        seek POS,WHENCE
        tell

NOTES
    Clearly, when wrapping a raw external filehandle (like \*STDOUT), I didn't want to close the
    file descriptor when the "wrapper" object is destroyed... since the user might not appreciate
    that! Hence, there's no DESTROY method in this class.

    When wrapping a FileHandle object, however, I believe that Perl will invoke the
    FileHandle::DESTROY when the last reference goes away, so in that case, the filehandle is closed
    if the wrapped FileHandle really was the last reference to it.

WARNINGS
    This module does not allow you to wrap filehandle names which are given as strings that lack the
    package they were opened in. That is, if a user opens FOO in package Foo, they must pass it to
    you either as "\*FOO" or as "Foo::FOO". However, "STDIN" and friends will work just fine.

VERSION
    $Id: Wrap.pm,v 1.2 2005/02/10 21:21:53 dfs Exp $

AUTHOR
    Primary Maintainer
        Dianne Skoll (dfs AT roaringpenguin.com).

    Original Author
        Eryq (eryq AT zeegee.com). President, ZeeGee Software Inc (http://www.zeegee.com).