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 buffer (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/setpos/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
specified padding) if you go to a location past the end, whereas
setpos() 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.