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



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
           David F. Skoll (dfs AT roaringpenguin.com).

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



perl v5.12.4                                2011-09-18                              IO::Wrap(3pm)