Document the NDBM_File and ODBM_File as SDBM_File

was documented in #6417.

p4raw-id: //depot/perl@6701

1 files changed, 84 insertions, 6 deletions

diff --git a/ext/NDBM_File/NDBM_File.pm b/ext/NDBM_File/NDBM_File.pm
index f98669f486..c9ef6993a8 100644
--- a/ext/NDBM_File/NDBM_File.pm
+++ b/ext/NDBM_File/NDBM_File.pm
@@ -24,15 +24,93 @@ NDBM_File - Tied access to ndbm files
 
 =head1 SYNOPSIS
 
- use NDBM_File;
- use Fcntl;       # for O_ constants
+  use Fcntl;   # For O_RDWR, O_CREAT, etc.
+  use NDBM_File;
 
- tie(%h, 'NDBM_File', 'Op.dbmx', O_RDWR|O_CREAT, 0640);
+  # Now read and change the hash
+  $h{newkey} = newvalue;
+  print $h{oldkey}; 
+  ...
+ 
+  untie %h;
+ 
+=head1 DESCRIPTION
+ 
+C<NDBM_File> establishes a connection between a Perl hash variable and
+a file in NDBM_File format;.  You can manipulate the data in the file
+just as if it were in a Perl hash, but when your program exits, the
+data will remain in the file, to be used the next time your program
+runs.
 
- untie %h;
+Use C<NDBM_File> with the Perl built-in C<tie> function to establish
+the connection between the variable and the file.  The arguments to
+C<tie> should be:
 
-=head1 DESCRIPTION
+=over 4
+
+=item 1.
+
+The hash variable you want to tie.
+
+=item 2. 
+
+The string C<"NDBM_File">.  (Ths tells Perl to use the C<NDBM_File>
+package to perform the functions of the hash.)
+
+=item 3. 
+
+The name of the file you want to tie to the hash.  
+
+=item 4.
+
+Flags.  Use one of:
+
+=over 2
+
+=item C<O_RDONLY>
+
+Read-only access to the data in the file.
+
+=item C<O_WRONLY>
+
+Write-only access to the data in the file.
+
+=item C<O_RDWR>
+
+Both read and write access.
+
+=back
+
+If you want to create the file if it does not exist, add C<O_CREAT> to
+any of these, as in the example.  If you omit C<O_CREAT> and the file
+does not already exist, the C<tie> call will fail.
+
+=item 5.
+
+The default permissions to use if a new file is created.  The actual
+permissions will be modified by the user's umask, so you should
+probably use 0666 here. (See L<perlfunc/umask>.)
+
+=back
+
+=head1 DIAGNOSTICS
+
+On failure, the C<tie> call returns an undefined value and probably
+sets C<$!> to contain the reason the file could not be tied.
+
+=head2 C<ndbm store returned -1, errno 22, key "..." at ...>
+
+This warning is emmitted when you try to store a key or a value that
+is too long.  It means that the change was not recorded in the
+database.  See BUGS AND WARNINGS below.
+
+=head1 BUGS AND WARNINGS
+
+There are a number of limits on the size of the data that you can
+store in the NDBM file.  The most important is that the length of a
+key, plus the length of its associated value, may not exceed 1008
+bytes.
 
-See L<perlfunc/tie>, L<perldbmfilter>
+See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
 
 =cut