IO::Wrap

IO::Wrap(3)	     User Contributed Perl Documentation	  IO::Wrap(3)



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::Han-
       dle 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::HAN-
	       DLE".  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
	   David F. Skoll (dfs@roaringpenguin.com).

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



perl v5.8.8			  2005-02-10			  IO::Wrap(3)