_60 & _04 - Add WRITE & CLOSE to TIEHANDLE

p4raw-id: //depot/perl@595

1 files changed, 161 insertions, 0 deletions

diff --git a/lib/Tie/Handle.pm b/lib/Tie/Handle.pm
new file mode 100644
index 0000000000..c7550530b8
--- /dev/null
+++ b/lib/Tie/Handle.pm
@@ -0,0 +1,161 @@
+package Tie::Handle;
+
+=head1 NAME
+
+Tie::Handle - base class definitions for tied handles
+
+=head1 SYNOPSIS
+
+    package NewHandle;
+    require Tie::Handle;
+     
+    @ISA = (Tie::Handle);
+     
+    sub READ { ... }		# Provide a needed method
+    sub TIEHANDLE { ... }	# Overrides inherited method
+         
+     
+    package main;
+    
+    tie *FH, 'NewHandle';
+
+=head1 DESCRIPTION
+
+This module provides some skeletal methods for handle-tying classes. See
+L<perltie> for a list of the functions required in tying a handle to a package.
+The basic B<Tie::Handle> package provides a C<new> method, as well as methods
+C<TIESCALAR>, C<FETCH> and C<STORE>. The C<new> method is provided as a means
+of grandfathering, for classes that forget to provide their own C<TIESCALAR>
+method.
+
+For developers wishing to write their own tied-handle classes, the methods
+are summarized below. The L<perltie> section not only documents these, but
+has sample code as well:
+
+=over
+
+=item TIEHANDLE classname, LIST
+
+The method invoked by the command C<tie *glob, classname>. Associates a new
+glob instance with the specified class. C<LIST> would represent additional
+arguments (along the lines of L<AnyDBM_File> and compatriots) needed to
+complete the association.
+
+=item WRITE this, scalar, length, offset
+
+Write I<length> bytes of data from I<scalar> starting at I<offset>.
+
+=item PRINT this, LIST
+
+Print the values in I<LIST>
+
+=item PRINTF this, format, LIST
+
+Print the values in I<LIST> using I<format>
+
+=item READ this, scalar, length, offset
+
+Read I<length> bytes of data into I<scalar> starting at I<offset>.
+
+=item READLINE this
+
+Read a single line
+
+=item GETC this
+
+Get a single character
+
+=item DESTROY this
+
+Free the storage associated with the tied handle referenced by I<this>.
+This is rarely needed, as Perl manages its memory quite well. But the
+option exists, should a class wish to perform specific actions upon the
+destruction of an instance.
+
+=back
+
+=head1 MORE INFORMATION
+
+The L<perltie> section contains an example of tying handles.
+
+=cut
+
+use Carp;
+
+sub new {
+    my $pkg = shift;
+    $pkg->TIEHANDLE(@_);
+}
+
+# "Grandfather" the new, a la Tie::Hash
+
+sub TIEHANDLE {
+    my $pkg = shift;
+    if (defined &{"{$pkg}::new"}) {
+	carp "WARNING: calling ${pkg}->new since ${pkg}->TIEHANDLE is missing"
+	    if $^W;
+	$pkg->new(@_);
+    }
+    else {
+	croak "$pkg doesn't define a TIEHANDLE method";
+    }
+}
+
+sub PRINT {
+    my $self = shift;
+    if($self->can('WRITE') != \&WRITE) {
+	my $buf = join(defined $, ? $, : "",@_);
+	$buf .= $\ if defined $\;
+	$self->WRITE($buf,length($buf),0);
+    }
+    else {
+	croak ref($self)," doesn't define a PRINT method";
+    }
+}
+
+sub PRINTF {
+    my $self = shift;
+    
+    if($self->can('WRITE') != \&WRITE) {
+	my $buf = sprintf(@_);
+	$self->WRITE($buf,length($buf),0);
+    }
+    else {
+	croak ref($self)," doesn't define a PRINTF method";
+    }
+}
+
+sub READLINE {
+    my $pkg = ref $_[0];
+    croak "$pkg doesn't define a READLINE method";
+}
+
+sub GETC {
+    my $self = shift;
+    
+    if($self->can('READ') != \&READ) {
+	my $buf;
+	$self->READ($buf,1);
+	return $buf;
+    }
+    else {
+	croak ref($self)," doesn't define a GETC method";
+    }
+}
+
+sub READ {
+    my $pkg = ref $_[0];
+    croak "$pkg doesn't define a READ method";
+}
+
+sub WRITE {
+    my $pkg = ref $_[0];
+    croak "$pkg doesn't define a WRITE method";
+}
+
+sub CLOSE {
+    my $pkg = ref $_[0];
+    croak "$pkg doesn't define a CLOSE method";
+}
+
+1;