io::handle::iterator(3pm) [debian man page]

IO::Handle::Iterator(3pm)				User Contributed Perl Documentation				 IO::Handle::Iterator(3pm)

NAME

       IO::Handle::Iterator - Iterator based read handle

SYNOPSIS

	   IO::Handle::Iterator->new(sub {
	       return $next_line; # or undef on eof
	   });

DESCRIPTION

       This class lets you define a read handle with a few fallback methods (like "read") using a single callback that behaves like "getline".

       This is similar but much simpler than:

	   IO::Handle::Prototype::Fallback->new(
	       __read => sub { ... },
	   );

       The reason being that the IO::Handle::Prototype::Fallback implementation will try its very best to behave correctly (i.e. respect the value
       of $/), whereas this implementation assumes it's fine to return things that aren't exactly lines from "getline", so the values are just
       passed through.

READ BUFFERING

       When a method that requires buffering is invoked the handle is reblessed to a subclass which handles buffering.

       Calling "getline" again on this object will return the value of the buffer and return to the normal iterator class.

perl v5.10.1							    2009-09-29						 IO::Handle::Iterator(3pm)

IO::Handle::Prototype::Fallback(3pm)			User Contributed Perl Documentation		      IO::Handle::Prototype::Fallback(3pm)

NAME

       IO::Handle::Prototype::Fallback - Create IO::Handle like objects using a set of callbacks.

SYNOPSIS

	   my $fh = IO::Handle::Prototype::Fallback->new(
	       getline => sub {
		   my $fh = shift;

		   ...
	       },
	   );

DESCRIPTION

       This class provides a way to define a filehandle based on callbacks.

       Fallback implementations are provided to the extent possible based on the provided callbacks, for both writing and reading.

SPECIAL CALLBACKS

       This class provides two additional methods on top of IO::Handle, designed to let you implement things with a minimal amount of baggage.

       The fallback methods are all best implemented using these, though these can be implemented in terms of Perl's standard methods too.

       However, to provide the most consistent semantics, it's better to do this:

	   IO::Handle::Prototype::Fallback->new(
	       __read => sub {
		   shift @array;
	       },
	   );

       Than this:

	   IO::Handle::Prototype::Fallback->new(
	       getline => sub {
		   shift @array;
	       },
	   );

       Because the fallback implementation of "getline" implements all of the extra crap you'd need to handle to have a fully featured
       implementation.

       __read
	   Return a chunk of data of any size (could use $/ or not, it depends on you, unlike "getline" which probably should respect the value of
	   $/).

	   This avoids the annoying "substr" stuff you need to do with "read".

       __write $string
	   Write out a string.

	   This is like a simplified "print", which can disregard $, and "$" as well as multiple argument forms, and does not have the extra
	   "substr" annoyance of "write" or "syswrite".

WRAPPING

       If you provide a single reading related callback ("__read", "getline" or "read") then your callback will be used to implement all of the
       other reading primitives using a string buffer.

       These implementations handle $/ in all forms ("undef", ref to number and string), all the funny calling conventions for "read", etc.

FALLBACKS

       Any callback that can be defined purely in terms of other callbacks in a way will be added. For instance "getc" can be implemented in terms
       of "read", "say" can be implemented in terms of "print", "print" can be implemented in terms of "write", "write" can be implemented in
       terms of "print", etc.

       None of these require special wrapping and will always be added if their dependencies are present.

GLOB OVERLOADING

       When overloaded as a glob a tied handle will be returned. This allows you to use the handle in Perl's IO builtins. For instance:

	   my $line = <$fh>

       will not call the "getline" method natively, but the tied interface arranges for that to happen.

perl v5.10.1							    2009-09-29				      IO::Handle::Prototype::Fallback(3pm)