IO::All - IO::All of it to Graham and Damian!


IO::All - IO::All of it to Graham and Damian!


    use IO::All;                                # Let the madness begin...
    # Some of the many ways to read a whole file into a scalar
    io('file.txt') > $contents;                 # Overloaded "arrow"
    $contents < io 'file.txt';                  # Flipped but same operation
    $io = io 'file.txt';                        # Create a new IO::All object
    $contents = $$io;                           # Overloaded scalar dereference
    $contents = $io->all;                       # A method to read everything
    $contents = $io->slurp;                     # Another method for that
    $contents = join '', $io->getlines;         # Join the separate lines
    $contents = join '', map "$_\n", @$io;      # Same. Overloaded array deref
    $io->tie;                                   # Tie the object as a handle
    $contents = join '', <$io>;                 # And use it in builtins
    # and the list goes on ...
    # Other file operations:
    @lines = io('file.txt')->slurp;             # List context slurp
    $content > io('file.txt');                  # Print to a file
    io('file.txt')->print($content, $more);     # (ditto)
    $content >> io('file.txt');                 # Append to a file
    io('file.txt')->append($content);           # (ditto)
    $content << $io;                            # Append to a string
    io('copy.txt') < io('file.txt');            $ Copy a file
    io('file.txt') > io('copy.txt');            # Invokes File::Copy
    io('more.txt') >> io('all.txt');            # Add on to a file
    # UTF-8 Support
    $contents = io('file.txt')->utf8->all;      # Turn on utf8
    use IO::All -utf8;                          # Turn on utf8 for all io
    $contents = io('file.txt')->all;            #   by default in this package.
    # General Encoding Support
    $contents = io('file.txt')->encoding('big5')->all;
    use IO::All -encoding => 'big5';            # Turn on big5 for all io
    $contents = io('file.txt')->all;            #   by default in this package.
    # Print the path name of a file:
    print $io->name;                            # The direct method
    print "$io";                                # Object stringifies to name
    print $io;                                  # Quotes not needed here
    print $io->filename;                        # The file portion only
    # Read all the files/directories in a directory:
    $io = io('my/directory/');                  # Create new directory object
    @contents = $io->all;                       # Get all contents of dir
    @contents = @$io;                           # Directory as an array
    @contents = values %$io;                    # Directory as a hash
    push @contents, $subdir                     # One at a time
      while $subdir = $io->next;
    # Print the name and file type for all the contents above:
    print "$_ is a " . $_->type . "\n"          # Each element of @contents
      for @contents;                            # is an IO::All object!!
    # Print first line of each file:
    print $_->getline                           # getline gets one line
      for io('dir')->all_files;                 # Files only
    # Print names of all files/dirs three directories deep:
    print "$_\n" for $io->all(3);               # Pass in the depth. Default=1
    # Print names of all files/dirs recursively:
    print "$_\n" for $io->all(0);               # Zero means all the way down
    print "$_\n" for $io->All;                  # Capitalized shortcut
    print "$_\n" for $io->deep->all;            # Another way
    # There are some special file names:
    print io('-');                              # Print STDIN to STDOUT
    io('-') > io('-');                          # Do it again
    io('-') < io('-');                          # Same. Context sensitive.
    "Bad puppy" > io('=');                      # Message to STDERR
    $string_file = io('$');                     # Create IO::String Object
    $temp_file = io('?');                       # Create a temporary file
    # Socket operations:
    $server = io('localhost:5555')->fork;       # Create a daemon socket
    $connection = $server->accept;              # Get a connection socket
    $input < $connection;                       # Get some data from it
    "Thank you!" > $connection;                 # Thank the caller
    $connection->close;                         # Hang up
    io(':6666')->accept->slurp > io->devnull;   # Take a complaint and file it
    # DBM database operations:
    $dbm = io 'my/database';                    # Create a database object
    print $dbm->{grocery_list};                 # Hash context makes it a DBM
    $dbm->{todo} = $new_list;                   # Write to database
    $dbm->dbm('GDBM_file');                     # Demand specific DBM
    io('mydb')->mldbm->{env} = \%ENV;           # MLDBM support
    # Tie::File support:
    $io = io 'file.txt';
    $io->[42] = 'Line Forty Three';             # Change a line
    print $io->[@$io / 2];                      # Print middle line
    @$io = reverse @$io;                        # Reverse lines in a file
    # Stat functions:
    printf "%s %s %s\n",                        # Print name, uid and size of 
      $_->name, $_->uid, $_->size               # contents of current directory
        for io('.')->all;
    print "$_\n" for sort                       # Use mtime method to sort all
      {$b->mtime <=> $a->mtime}                 # files under current directory
        io('.')->All_Files;                     # by recent modification time.
    # File::Spec support:
    $contents < io->catfile(qw(dir file.txt));  # Portable IO operation
    # Miscellaneous:
    @lines = io('file.txt')->chomp->slurp;      # Chomp as you slurp
    @chunks = 
      io('file.txt')->separator('xxx')->slurp;  # Use alternnate record sep
    $binary = io('file.bin')->binary->all;      # Read a binary file
    io('a-symlink')->readlink->slurp;           # Readlink returns an object
    print io('foo')->absolute->pathname;        # Print absolute path of foo
    # IO::All External Plugin Methods
    io("myfile") > io->("";);     # Upload a file using ftp
    $html < io->http("");         # Grab a web page
    io('')->print($spam); # Email a "friend"
    # This is just the beginning, read on...


``Graham Barr for doing it all. Damian Conway for doing it all different.''

IO::All combines all of the best Perl IO modules into a single nifty object oriented interface to greatly simplify your everyday Perl IO idioms. It exports a single function called io, which returns a new IO::All object. And that object can do it all!

The IO::All object is a proxy for IO::File, IO::Dir, IO::Socket, IO::String, Tie::File, File::Spec, File::Path and File::ReadBackwards; as well as all the DBM and MLDBM modules. You can use most of the methods found in these classes and in IO::Handle (which they inherit from). IO::All adds dozens of other helpful idiomatic methods including file stat and manipulation functions.

IO::All is pluggable, and modules like IO::All::LWP and IO::All::Mailto add even more functionality. Optionally, every IO::All object can be tied to itself. This means that you can use most perl IO builtins on it: readline, <>, getc, print, printf, syswrite, sysread, close.

The distinguishing magic of IO::All is that it will automatically open (and close) files, directories, sockets and other IO things for you. You never need to specify the mode ('<', '>>', etc), since it is determined by the usage context. That means you can replace this:

    open STUFF, '<', './mystuff'
      or die "Can't open './mystuff' for input:\n$!";
    local $/;
    my $stuff = <STUFF>;
    close STUFF;

with this:

    my $stuff < io"./mystuff";

And that is a good thing!


Normally just say:

    use IO::All;

and IO::All will export a single function called io, which contructs all IO objects.

You can also pass global flags like this:

    use IO::All -strict -encoding => 'big5', -foobar;

Which automatically makes those method calls on every new IO object. In other words this:

    my $io = io('lalala.txt');

becomes this:

    my $io = io('lalala.txt')->strict->encoding('big5')->foobar;


Here is an alphabetical list of all the public methods that you can call on an IO::All object.

abs2rel, absolute, accept, All, all, All_Dirs, all_dirs, All_Files, all_files, All_Links, all_links, append, appendf, appendln, assert, atime, autoclose, autoflush, backwards, bcc, binary, binmode, blksize, blocks, block_size, buffer, canonpath, case_tolerant, catdir, catfile, catpath, cc, chdir, chomp, clear, close, confess, content, ctime, curdir, dbm, deep, device, device_id, devnull, dir, domain, empty, encoding, eof, errors, file, filename, fileno, filepath, filter, fork, from, ftp, get, getc, getline, getlines, gid, handle, head, http, https, inode, io_handle, is_absolute, is_dir, is_dbm, is_executable, is_file, is_link, is_mldbm, is_open, is_pipe, is_readable, is_socket, is_stdio, is_string, is_temp, is_writable, join, length, link, lock, mailer, mailto, mkdir, mkpath, mldbm, mode, modes, mtime, name, new, next, nlink, open, password, path, pathname, perms, pipe, port, print, printf, println, put, rdonly, rdwr, read, readdir, readlink, recv, rel2abs, relative, rename, request, response, rmdir, rmtree, rootdir, scalar, seek, send, separator, shutdown, size, slurp, socket, sort, splitdir, splitpath, stat, stdio, stderr, stdin, stdout, strict, string, string_ref, subject, sysread, syswrite, tail, tell, temp, tie, tmpdir, to, touch, truncate, type, user, uid, unlink, unlock, updir, uri, utf8, utime and write.

Each method is documented further below.


IO::All objects overload a small set of Perl operators to great effect. The overloads are limited to <, <<, >, >>, dereferencing operations, and stringification.

Even though relatively few operations are overloaded, there is actually a huge matrix of possibilities for magic. That's because the overloading is sensitive to the types, position and context of the arguments, and an IO::All object can be one of many types.

The most important overload to grok is stringification. IO::All objects stringify to their file or directory name. Here we print the contents of the current directory:

    perl -MIO::All -le 'print for io(".")->all'

is the same as:

    perl -MIO::All -le 'print $_->name for io(".")->all'

Stringification is important because it allows IO::All operations to return objects when they might otherwise return file names. Then the recipient can use the result either as an object or a string.

'>' and '<' move data between objects in the direction pointed to by the operator.

    $content1 < io('file1');
    $content1 > io('file2');
    io('file2') > $content3;
    io('file3') < $content3;
    io('file3') > io('file4');
    io('file5') < io('file4');

'>>' and '<<' do the same thing except the recipent string or file is appended to.

An IO::All file used as an array reference becomes tied using Tie::File:

    $file = io"file";
    # Print last line of file
    print $file->[-1];
    # Insert new line in middle of file
    $file->[$#$file / 2] = 'New line';

An IO::All file used as a hash reference becomes tied to a DBM class:

    io('mydbm')->{ingy} = 'YAML';

An IO::All directory used as an array reference, will expose each file or subdirectory as an element of the array.

    print "$_\n" for @{io 'dir'};

IO::All directories used as hash references have file names as keys, and IO::All objects as values:

    print io('dir')->{'foo.txt'}->slurp;

Files used as scalar references get slurped:

    print ${io('dir')->{'foo.txt'}};

Not all combinations of operations and object types are supported. Some just haven't been added yet, and some just don't make sense. If you use an invalid combination, an error will be thrown.


This section describes some various things that you can easily cook up with IO::All.

File Locking

IO::All makes it very easy to lock files. Just use the lock method. Here's a standalone program that demonstrates locking for both write and read:

    use IO::All;
    my $io1 = io('myfile')->lock;
    $io1->println('line 1');
    fork or do {
        my $io2 = io('myfile')->lock;
        print $io2->slurp;
    sleep 1;
    $io1->println('line 2');
    $io1->println('line 3');

There are a lot of subtle things going on here. An exclusive lock is issued for $io1 on the first println. That's because the file isn't actually opened until the first IO operation.

When the child process tries to read the file using $io2, there is a shared lock put on it. Since $io1 has the exclusive lock, the slurp blocks.

The parent process sleeps just to make sure the child process gets a chance. The parent needs to call unlock or close to release the lock. If all goes well the child will print 3 lines.

Round Robin

This simple example will read lines from a file forever. When the last line is read, it will reopen the file and read the first one again.

    my $io = io'file1.txt';
    while (my $line = $io->getline || $io->getline) {
        print $line;

Reading Backwards

If you call the backwards method on an IO::All object, the getline and getlines will work in reverse. They will read the lines in the file from the end to the beginning.

    my @reversed;
    my $io = io('file1.txt');
    while (my $line = $io->getline) {
        push @reversed, $line;

or more simply:

    my @reversed = io('file1.txt')->backwards->getlines;

The backwards method returns the IO::All object so that you can chain the calls.

NOTE: This operation requires that you have the File::ReadBackwards module installed.

=head2 Client/Server Sockets

IO::All makes it really easy to write a forking socket server and a client to talk to it.

In this example, a server will return 3 lines of text, to every client that calls it. Here is the server code:

    use IO::All;
    my $socket = io(':12345')->fork->accept;
    $socket->print($_) while <DATA>;
    On your mark,
    Get set,

Here is the client code:

    use IO::All;
    my $io = io('localhost:12345');
    print while $_ = $io->getline;

You can run the server once, and then run the client repeatedly (in another terminal window). It should print the 3 data lines each time.

Note that it is important to close the socket if the server is forking, or else the socket won't go out of scope and close.

A Tiny Web Server

Here is how you could write a simplistic web server that works with static and dynamic pages:

    perl -MIO::All -e 'io(":8080")->fork->accept->(sub { $_[0] < io(-x $1 ? "./$1 |" : $1) if /^GET \/(.*) / })'

There is are a lot of subtle things going on here. First we accept a socket and fork the server. Then we overload the new socket as a code ref. This code ref takes one argument, another code ref, which is used as a callback.

The callback is called once for every line read on the socket. The line is put into $_ and the socket itself is passed in to the callback.

Our callback is scanning the line in $_ for an HTTP GET request. If one is found it parses the file name into $1. Then we use $1 to create an new IO::All file object... with a twist. If the file is executable (-x), then we create a piped command as our IO::All object. This somewhat approximates CGI support.

Whatever the resulting object is, we direct the contents back at our socket which is in $_[0]. Pretty simple, eh?

DBM Files

IO::All file objects used as a hash reference, treat the file as a DBM tied to a hash. Here I write my DB record to STDERR:

    io("names.db")->{ingy} > io'=';

Since their are several DBM formats available in Perl, IO::All picks the first one of these that is installed on your system:

    DB_File GDBM_File NDBM_File ODBM_File SDBM_File

You can override which DBM you want for each IO::All object:

    my @keys = keys %{io('mydbm')->dbm('SDBM_File')};

File Subclassing

Subclassing is easy with IO::All. Just create a new module and use IO::All as the base class, like this:

    package NewModule;
    use IO::All -base;

You need to do it this way so that IO::All will export the io function. Here is a simple recipe for subclassing:

IO::Dumper inherits everything from IO::All and adds an extra method called dump, which will dump a data structure to the file we specify in the io function. Since it needs Data::Dumper to do the dumping, we override the open method to require Data::Dumper and then pass control to the real open.

First the code using the module:

    use IO::Dumper;

And next the IO::Dumper module itself:

    package IO::Dumper;
    use IO::All -base;
    use Data::Dumper;
    sub dump {
        my $self = shift;
        Dumper(@_) > $self;

Inline Subclassing

This recipe does the same thing as the previous one, but without needing to write a separate module. The only real difference is the first line. Since you don't ``use'' IO::Dumper, you need to still call its import method manually.

    package IO::Dumper;
    use IO::All -base;
    use Data::Dumper;
    sub dump {
        my $self = shift;
        Dumper(@_) > $self;


This section gives a full description of all of the methods that you can call on IO::All objects. The methods have been grouped into subsections based on object construction, option settings, configuration, action methods and support for specific modules.

Object Construction and Initialization Methods

If you need to use the same options to create a lot of objects, and don't want to duplicate the code, just create a dummy object with the options you want, and use that object to spawn other objects.

    my $lt = io->lock->tie;
    my $io1 = $lt->new('file1');
    my $io2 = $lt->new('file2');

Since the new method copies attributes from the calling object, both $io1 and $io2 will be locked and tied.

Option Setting Methods

The following methods don't do any actual I/O, but they specify options about how the I/O should be done.

Each option can take a single argument of 0 or 1. If no argument is given, the value 1 is assumed. Passing 0 turns the option off.

All of these options return the object reference that was used to invoke them. This is so that the option methods can be chained together. For example:

    my $io = io('path/file')->tie->assert->chomp->lock;

Configuration Methods

The following methods don't do any actual I/O, but they set specific values to configure the IO::All object.

If these methods are passed no argument, they will return their current value. If arguments are passed they will be used to set the current value, and the object reference will be returned for potential method chaining.

IO Action Methods

These are the methods that actually perform I/O operations on an IO::All object. The stat methods and the File::Spec methods are documented in separate sections below.

Stat Methods

This methods get individual values from a stat call on the file, directory or handle represented by th IO::All object.

File::Spec Methods

These methods are all adaptations from File::Spec. Each method actually does call the matching File::Spec method, but the arguments and return values differ slightly. Instead of being file and directory names, they are IO::All objects. Since IO::All objects stringify to their names, you can generally use the methods just like File::Spec.



The goal of the IO::All project is to continually refine the module to be as simple and consistent to use as possible. Therefore, in the early stages of the project, I will not hesitate to break backwards compatibility with other versions of IO::All if I can find an easier and clearer way to do a particular thing.

IO is tricky stuff. There is definitely more work to be done. On the other hand, this module relies heavily on very stable existing IO modules; so it may work fairly well.

I am sure you will find many unexpected ``features''. Please send all problems, ideas and suggestions to

Known Bugs and Deficiencies

Not all possible combinations of objects and methods have been tested. There are many many combinations. All of the examples have been tested. If you find a bug with a particular combination of calls, let me know.

If you call a method that does not make sense for a particular object, the result probably won't make sense. Little attempt is made to check for improper usage.


IO::Handle, IO::File, IO::Dir, IO::Socket, IO::String, File::Spec, File::Path, File::ReadBackwards, Tie::File


A lot of people have sent in suggestions, that have become a part of IO::All. Thank you.

Special thanks to Ian Langworth for continued testing and patching.

Thank you Simon Cozens for tipping me off to the overloading possibilities.

Finally, thanks to Autrijus Tang, for always having one more good idea.

(It seems IO::All of it to a lot of people!)


Ingy döt Net <>


Copyright (c) 2004. Brian Ingerson. All rights reserved.

Copyright (c) 2006. Ingy döt Net. All rights reserved.

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


 IO::All - IO::All of it to Graham and Damian!