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String(3pm)           User Contributed Perl Documentation          String(3pm)



NAME
       IO::String - Emulate file interface for in-core strings

SYNOPSIS
        use IO::String;
        $io = IO::String->new;
        $io = IO::String->new($var);
        tie *IO, 'IO::String';

        # read data
        <$io>;
        $io->getline;
        read($io, $buf, 100);

        # write data
        print $io "string\n";
        $io->print(@data);
        syswrite($io, $buf, 100);

        select $io;
        printf "Some text %s\n", $str;

        # seek
        $pos = $io->getpos;
        $io->setpos(0);        # rewind
        $io->seek(-30, -1);
        seek($io, 0, 0);

DESCRIPTION
       The "IO::String" module provides the "IO::File" interface for in-core
       strings.  An "IO::String" object can be attached to a string, and makes
       it possible to use the normal file operations for reading or writing
       data, as well as for seeking to various locations of the string.  This
       is useful when you want to use a library module that only provides an
       interface to file handles on data that you have in a string variable.

       Note that perl-5.8 and better has built-in support for "in memory"
       files, which are set up by passing a reference instead of a filename to
       the open() call. The reason for using this module is that it makes the
       code backwards compatible with older versions of Perl.

       The "IO::String" module provides an interface compatible with
       "IO::File" as distributed with IO-1.20, but the following methods are
       not available: new_from_fd, fdopen, format_write, format_page_number,
       format_lines_per_page, format_lines_left, format_name, format_top_name.

       The following methods are specific to the "IO::String" class:

       $io = IO::String->new
       $io = IO::String->new( $string )
           The constructor returns a newly-created "IO::String" object.  It
           takes an optional argument, which is the string to read from or
           write into.  If no $string argument is given, then an internal buf-
           fer (initially empty) is allocated.

           The "IO::String" object returned is tied to itself.  This means
           that you can use most Perl I/O built-ins on it too: readline, <>,
           getc, print, printf, syswrite, sysread, close.

       $io->open
       $io->open( $string )
           Attaches an existing IO::String object to some other $string, or
           allocates a new internal buffer (if no argument is given).  The
           position is reset to 0.

       $io->string_ref
           Returns a reference to the string that is attached to the
           "IO::String" object.  Most useful when you let the "IO::String"
           create an internal buffer to write into.

       $io->pad
       $io->pad( $char )
           Specifies the padding to use if the string is extended by either
           the seek() or truncate() methods.  It is a single character and
           defaults to "\0".

       $io->pos
       $io->pos( $newpos )
           Yet another interface for reading and setting the current
           read/write position within the string (the normal getpos/set-
           pos/tell/seek methods are also available).  The pos() method always
           returns the old position, and if you pass it an argument it sets
           the new position.

           There is (deliberately) a difference between the setpos() and
           seek() methods in that seek() extends the string (with the speci-
           fied padding) if you go to a location past the end, whereas set-
           pos() just snaps back to the end.  If truncate() is used to extend
           the string, then it works as seek().

BUGS
       In Perl versions < 5.6, the TIEHANDLE interface was incomplete.  If you
       use such a Perl, then seek(), tell(), eof(), fileno(), binmode() will
       not do anything on an "IO::String" handle.  See perltie for details.

SEE ALSO
       IO::File, IO::Stringy, "open" in perlfunc

COPYRIGHT
       Copyright 1998-2005 Gisle Aas.

       This library is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.



perl v5.8.8                       2006-11-17                       String(3pm)