Document that there are bugs with EBCDIC and regexes

[perl5.git] / pod / perldbmfilter.pod

diff --git a/pod/perldbmfilter.pod b/pod/perldbmfilter.pod
index d62e496..e58ce20 100644 (file)
--- a/pod/perldbmfilter.pod
+++ b/pod/perldbmfilter.pod
@@ -6,10 +6,10 @@ perldbmfilter - Perl DBM Filters
 
     $db = tie %hash, 'DBM', ...
 
-    $old_filter = $db->filter_store_key  ( sub { ... } ) ;
-    $old_filter = $db->filter_store_value( sub { ... } ) ;
-    $old_filter = $db->filter_fetch_key  ( sub { ... } ) ;
-    $old_filter = $db->filter_fetch_value( sub { ... } ) ;
+    $old_filter = $db->filter_store_key  ( sub { ... } );
+    $old_filter = $db->filter_store_value( sub { ... } );
+    $old_filter = $db->filter_fetch_key  ( sub { ... } );
+    $old_filter = $db->filter_fetch_value( sub { ... } );
 
 =head1 DESCRIPTION
 
@@ -61,7 +61,7 @@ When each filter is called by Perl, a local copy of C<$_> will contain
 the key or value to be filtered. Filtering is achieved by modifying
 the contents of C<$_>. The return code from the filter is ignored.
 
-=head2 An Example -- the NULL termination problem.
+=head2 An Example: the NULL termination problem.
 
 DBM Filters are useful for a class of problems where you I<always>
 want to make the same transformation to all keys, all values or both.
@@ -73,7 +73,7 @@ when Perl writes to DBM databases it doesn't use NULL termination, so
 your Perl application will have to manage NULL termination itself. When
 you write to the database you will have to use something like this:
 
-    $hash{"$key\0"} = "$value\0" ;
+    $hash{"$key\0"} = "$value\0";
 
 Similarly the NULL needs to be taken into account when you are considering
 the length of existing keys/values.
@@ -85,30 +85,30 @@ the database and have them removed when you read from the database. As I'm
 sure you have already guessed, this is a problem that DBM Filters can
 fix very easily.
 
-    use strict ;
-    use warnings ;
-    use SDBM_File ;
-    use Fcntl ;
+    use strict;
+    use warnings;
+    use SDBM_File;
+    use Fcntl;
 
-    my %hash ;
-    my $filename = "filt" ;
-    unlink $filename ;
+    my %hash;
+    my $filename = "filt";
+    unlink $filename;
 
     my $db = tie(%hash, 'SDBM_File', $filename, O_RDWR|O_CREAT, 0640)
-      or die "Cannot open $filename: $!\n" ;
+      or die "Cannot open $filename: $!\n";
 
     # Install DBM Filters
-    $db->filter_fetch_key  ( sub { s/\0$//    } ) ;
-    $db->filter_store_key  ( sub { $_ .= "\0" } ) ;
+    $db->filter_fetch_key  ( sub { s/\0$//    } );
+    $db->filter_store_key  ( sub { $_ .= "\0" } );
     $db->filter_fetch_value( 
-        sub { no warnings 'uninitialized' ;s/\0$// } ) ;
-    $db->filter_store_value( sub { $_ .= "\0" } ) ;
+        sub { no warnings 'uninitialized'; s/\0$// } );
+    $db->filter_store_value( sub { $_ .= "\0" } );
 
-    $hash{"abc"} = "def" ;
-    my $a = $hash{"ABC"} ;
+    $hash{"abc"} = "def";
+    my $a = $hash{"ABC"};
     # ...
-    undef $db ;
-    untie %hash ;
+    undef $db;
+    untie %hash;
 
 The code above uses SDBM_File, but it will work with any of the DBM
 modules.
@@ -118,13 +118,13 @@ self-explanatory. Both "fetch" filters remove the terminating NULL,
 and both "store" filters add a terminating NULL.
 
 
-=head2 Another Example -- Key is a C int.
+=head2 Another Example: Key is a C int.
 
 Here is another real-life example. By default, whenever Perl writes to
 a DBM database it always writes the key and value as strings. So when
 you use this:
 
-    $hash{12345} = "something" ;
+    $hash{12345} = "something";
 
 the key 12345 will get stored in the DBM database as the 5 byte string
 "12345". If you actually want the key to be stored in the DBM database
@@ -133,28 +133,28 @@ when reading.
 
 Here is a DBM Filter that does it:
 
-    use strict ;
-    use warnings ;
-    use DB_File ;
-    my %hash ;
-    my $filename = "filt" ;
-    unlink $filename ;
+    use strict;
+    use warnings;
+    use DB_File;
+    my %hash;
+    my $filename = "filt";
+    unlink $filename;
 
 
     my $db = tie %hash, 'DB_File', $filename, O_CREAT|O_RDWR, 0666, $DB_HASH 
-      or die "Cannot open $filename: $!\n" ;
+      or die "Cannot open $filename: $!\n";
 
-    $db->filter_fetch_key  ( sub { $_ = unpack("i", $_) } ) ;
-    $db->filter_store_key  ( sub { $_ = pack ("i", $_) } ) ;
-    $hash{123} = "def" ;
+    $db->filter_fetch_key  ( sub { $_ = unpack("i", $_) } );
+    $db->filter_store_key  ( sub { $_ = pack ("i", $_) } );
+    $hash{123} = "def";
     # ...
-    undef $db ;
-    untie %hash ;
+    undef $db;
+    untie %hash;
 
 The code above uses DB_File, but again it will work with any of the
 DBM modules.
 
-This time only two filters have been used -- we only need to manipulate
+This time only two filters have been used; we only need to manipulate
 the contents of the key, so it wasn't necessary to install any value
 filters.