package IO::Wrap; # SEE DOCUMENTATION AT BOTTOM OF FILE require 5.002; use strict; use vars qw(@ISA @EXPORT $VERSION); @ISA = qw(Exporter); @EXPORT = qw(wraphandle); use FileHandle; use Carp; # The package version, both in 1.23 style *and* usable by MakeMaker: $VERSION = "2.110"; #------------------------------ # wraphandle RAW #------------------------------ sub wraphandle { my $raw = shift; new IO::Wrap $raw; } #------------------------------ # new STREAM #------------------------------ sub new { my ($class, $stream) = @_; no strict 'refs'; ### Convert raw scalar to globref: ref($stream) or $stream = \*$stream; ### Wrap globref and incomplete objects: if ((ref($stream) eq 'GLOB') or ### globref (ref($stream) eq 'FileHandle') && !defined(&FileHandle::read)) { return bless \$stream, $class; } $stream; ### already okay! } #------------------------------ # I/O methods... #------------------------------ sub close { my $self = shift; return close($$self); } sub getline { my $self = shift; my $fh = $$self; return scalar(<$fh>); } sub getlines { my $self = shift; wantarray or croak("Can't call getlines in scalar context!"); my $fh = $$self; <$fh>; } sub print { my $self = shift; print { $$self } @_; } sub read { my $self = shift; return read($$self, $_[0], $_[1]); } sub seek { my $self = shift; return seek($$self, $_[0], $_[1]); } sub tell { my $self = shift; return tell($$self); } #------------------------------ 1; __END__ =head1 NAME IO::Wrap - wrap raw filehandles in IO::Handle interface =head1 SYNOPSIS use IO::Wrap; ### Do stuff with any kind of filehandle (including a bare globref), or ### any kind of blessed object that responds to a print() message. ### sub do_stuff { my $fh = shift; ### At this point, we have no idea what the user gave us... ### a globref? a FileHandle? a scalar filehandle name? $fh = wraphandle($fh); ### At this point, we know we have an IO::Handle-like object! $fh->print("Hey there!"); ... } =head1 DESCRIPTION Let's say you want to write some code which does I/O, but you don't want to force the caller to provide you with a FileHandle or IO::Handle object. You want them to be able to say: do_stuff(\*STDOUT); do_stuff('STDERR'); do_stuff($some_FileHandle_object); do_stuff($some_IO_Handle_object); And even: do_stuff($any_object_with_a_print_method); Sure, one way to do it is to force the caller to use tiehandle(). But that puts the burden on them. Another way to do it is to use B, which provides you with the following functions: =over 4 =item wraphandle SCALAR This function will take a single argument, and "wrap" it based on what it seems to be... =over 4 =item * B like C<"STDOUT"> or C<"Class::HANDLE">. In this case, the filehandle name is wrapped in an IO::Wrap object, which is returned. =item * B like C<\*STDOUT>. In this case, the filehandle glob is wrapped in an IO::Wrap object, which is returned. =item * B In this case, the FileHandle is wrapped in an IO::Wrap object if and only if your FileHandle class does not support the C method. =item * B which is assumed to be already conformant to the IO::Handle interface. In this case, you just get back that object. =back =back If you get back an IO::Wrap object, it will obey a basic subset of the IO:: interface. That is, the following methods (note: I said I, not named operators) should work on the thing you get back: close getline getlines print ARGS... read BUFFER,NBYTES seek POS,WHENCE tell =head1 NOTES Clearly, when wrapping a raw external filehandle (like \*STDOUT), I didn't want to close the file descriptor when the "wrapper" object is destroyed... since the user might not appreciate that! Hence, there's no DESTROY method in this class. When wrapping a FileHandle object, however, I believe that Perl will invoke the FileHandle::DESTROY when the last reference goes away, so in that case, the filehandle is closed if the wrapped FileHandle really was the last reference to it. =head1 WARNINGS This module does not allow you to wrap filehandle names which are given as strings that lack the package they were opened in. That is, if a user opens FOO in package Foo, they must pass it to you either as C<\*FOO> or as C<"Foo::FOO">. However, C<"STDIN"> and friends will work just fine. =head1 VERSION $Id: Wrap.pm,v 1.2 2005/02/10 21:21:53 dfs Exp $ =head1 AUTHOR =item Primary Maintainer David F. Skoll (F). =item Original Author Eryq (F). President, ZeeGee Software Inc (F). =cut