NAME

       IO::Handle::Util - Functions for working with IO::Handle like objects.

SYNOPSIS

           # make something that looks like a filehandle from a random data:
           my $io = io_from_any $some_data;

           # or from a callback that returns strings:
           my $io = io_from_getline sub { return $another_line };

           # create a callback that iterates through the handle
           my $read_cb = io_to_read_cb $io;

DESCRIPTION

       This module provides a number of helpful routines to manipulate or create IO::Handle like
       objects.

EXPORTS

   Coercions resulting in IO objects
       These are available using the ":io_from" export group.

       io_from_any $whatever
           Inspects the value of "whatever" and calls the appropriate coercion function on it,
           either "io_from_ref" or "io_from_string".

       io_from_ref $some_ref
           Depending on the reference type of $some_ref invokes either "io_from_object",
           "io_from_array" or "io_from_scalar_ref".

           Code references are not coerced automatically because either "io_from_thunk" or
           "io_from_getline" or "io_from_write_cb" could all make sense.

           Globs are returned as is only if they have a valid "IO" slot.

       io_from_object $obj
           Depending on the class of $obj either returns or coerces the object.

       Objects that are passed through include anything that subclasses IO::Handle or seems to
       duck type (supports the "print" and "getline" methods, which might be a bit too
       permissive).

       Objects that are coerced currently only include Path::Class::File, which will have the
       "openr" method invoked on it.

       Anything else is an error.

       io_from_string $str
           Instantiates an IO::String object using $str as the buffer.

           Note that $str is not passed as an alias, so writing to the IO object will not modify
           string. For that see "io_from_scalar_ref".

       io_from_array \@array
           Creates an IO::Handle::Iterator that will return the elements of @array one by one.

           Note that a copy of @array is made.

           In order to be able to append more elements to the array or remove the ones that have
           been returned use IO::Handle::Iterator yourself directly.

       io_from_scalar_ref \$str
           Creates an IO::String object using $str as the buffer.

           Writing to the IO object will modify $str.

       io_from_thunk sub { ... }
           Invokes the callback once in list context the first time it's needed, and then returns
           each element of the list like "io_from_array" would.

       io_from_getline sub { ... }
           Creates an IO::Handle::Iterator object using the callback.

       io_from_write_cb sub { ... }
           Creates an IO::Handle::Prototype::Fallback using the callback.

           The callback will always be invoked with one string argument and with the values of $,
           and "$\" localized to "undef".

   Coercions utilizing IO objects
       These coercions will actually call "io_from_any" on their argument first. This allows you
       to do things like:

           my $str = '';
           my $sub = io_to_write_cb(\$str);

           $sub->("foo");

       These are available using the ":io_to" export group.

       io_to_write_cb $thing
           Creates a code ref that will invoke "print" on the handle with the arguments to the
           callback.

           $, and "$\" will both be localized to "undef".

       io_to_read_cb $thing
           Creates a code ref that will invoke "getline" on the handle.

           $/ will not be localized and should probably be set to a reference to a number if you
           want efficient iteration. See perlvar for details.

       io_to_string $thing
           Slurps a string out of the IO object by reading all the data.

           If a string was passed it is returned as is.

       io_to_array $thing
           Returns an array reference containing all the lines of the IO object.

           If an array reference was passed it is returned as is.

       io_to_list $thing
           Returns the list of lines from the IO object.

           Warns if not invoked in list context.

           If an array reference was passed it is dereferenced an its elements are returned.

       io_to_glob $thing
           If the filehandle is an unblessed glob returns it as is, otherwise returns a new glob
           which is tied to delegate to the OO interface.

           This lets you use most of the builtins without the method syntax:

               my $fh = io_to_glob($some_kind_of_OO_handle);

               while ( defined( my $line = <$fh> ) ) {
                   ...
               }

   Misc functions
       io_prototype %callbacks
           Given a key-value pair list of named callbacks, constructs an
           IO::Handle::Prototype::Fallback object with those callbacks.

           For example:

               my $io = io_prototype print => sub {
                   my $self = shift;

                   no warnings 'uninitialized';
                   $string .= join($,, @_) . $\;
               };

               $io->say("Hello"); # $string now has "Hello\n"

           See IO::Handle::Prototype::Fallback for more details.

       is_real_fh $io
           Returns true if the IO handle probably could be passed to something like
           AnyEvent::Handle which would break encapsulation.

           Checks for the following conditions:

           •   The handle has a reftype of either a "GLOB" with an "IO" slot, or is an "IO"
               itself.

           •   The handle's "fileno" method returns a positive number, corresponding to a
               filedescriptor.

           •   The "fileno" builtin returns the same thing as "fileno" invoked as a method.

           If these conditions hold the handle is probably OK to work with using the IO builtins
           directly, or passing the filedesctiptor to C land, instead of by invoking methods on
           it.

SEE ALSO

       IO::Handle, FileHandle, IO::String, perlio, "open" in perlfunc

VERSION CONTROL

       <http://github.com/nothingmuch/io-handle-util>

AUTHOR

       Yuval Kogman

COPYRIGHT & LICENSE

               Copyright (c) 2009 Yuval Kogman. All rights reserved
               This program is free software; you can redistribute
               it and/or modify it under the same terms as Perl itself.