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

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

          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!");

       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:


       And even:


       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...

           o   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.

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

           o   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.

           o   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:

           print ARGS...
           read BUFFER,NBYTES
           seek POS,WHENCE

       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.

       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

       $Id:,v 1.2 2005/02/10 21:21:53 dfs Exp $

       Primary Maintainer
           David F. Skoll (

       Original Author
           Eryq (  President, ZeeGee Software Inc

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

Czas wygenerowania: 0.00080 sek.

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