String(3pm) User Contributed Perl Documentation String(3pm)
IO::String - Emulate file interface for in-core strings
$io = IO::String->new;
$io = IO::String->new($var);
tie *IO, 'IO::String';
# read data
read($io, $buf, 100);
# write data
print $io "string\n";
syswrite($io, $buf, 100);
printf "Some text %s\n", $str;
$pos = $io->getpos;
$io->setpos(0); # rewind
seek($io, 0, 0);
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( $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.
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( $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( $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().
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.
IO::File, IO::Stringy, "open" in perlfunc
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)