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 dostuff {
              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:

           dostuff(\*STDOUT);
           dostuff('STDERR');
           dostuff($someFileHandleobject);
           dostuff($someIOHandleobject);

       And even:

           dostuff($anyobjectwithaprintmethod);

       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 IIOO::::WWrraapp,
       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...

           +o   AA rraaww ssccaallaarr ffiilleehhaannddllee nnaammee,, like "STDOUT" or "Class::HANDLE".
               In this case, the filehandle name is wrapped in an IO::Wrap
               object, which is returned.

           +o   AA rraaww ffiilleehhaannddllee gglloobb,, like "\*STDOUT".  In this case, the
               filehandle glob is wrapped in an IO::Wrap object, which is
               returned.

           +o   AA bblleesssseedd FFiilleeHHaannddllee oobbjjeecctt..  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.

           +o   AAnnyy ootthheerr kkiinndd ooff bblleesssseedd oobbjjeecctt,, 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

NNOOTTEESS
       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.

WWAARRNNIINNGGSS
       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.

VVEERRSSIIOONN
       $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).

PPOODD EERRRROORRSS
       e! The above document had some coding errors, which are explained       bbeellooww::

       Around line 212:
           '=item' outside of any '=over'



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