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 = "2.111";
#------------------------------
# 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($$self);
}
sub fileno {
my $self = shift;
my $fh = $$self;
return fileno($fh);
}
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<IO::Wrap>, 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<A raw scalar filehandle name,> 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<A raw filehandle glob,> like C<\*STDOUT>.
In this case, the filehandle glob is wrapped in an IO::Wrap object,
which is returned.
=item *
B<A blessed FileHandle object.>
In this case, the FileHandle is wrapped in an IO::Wrap object if and only
if your FileHandle class does not support the C<read()> method.
=item *
B<Any other kind of blessed object,> 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<methods>, 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
=over 4
=item Primary Maintainer
Dianne Skoll (F<dfs@roaringpenguin.com>).
=item Original Author
Eryq (F<eryq@zeegee.com>).
President, ZeeGee Software Inc (F<http://www.zeegee.com>).
=back
=cut
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