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From: sommar@enea.UUCP (Erland Sommarskog)
Newsgroups: comp.os.vms
Subject: Contemplations on CDU
Message-ID: <1935@enea.UUCP>
Date: Sat, 30-May-87 12:35:51 EDT
Article-I.D.: enea.1935
Posted: Sat May 30 12:35:51 1987
Date-Received: Mon, 1-Jun-87 06:40:11 EDT
Reply-To: sommar@enea.UUCP(Erland Sommarskog)
Followup-To: comp.os.vms
Organization: ENEA DATA Svenska AB, Sweden
Lines: 37


CDU is a nice facility, really useful for defining your own commands.
However, I'm not really on terms with it in some cases. Look at the 
following excerpt:
   Define type DESCRIPTION_WORDS
       Keyword HEADER  deafult, nonnegatable, value(default=0)
       Keyword FOOT    deafult, nonnegatable, value(default=0)
       Keyword PAGE    deafult, nonnegatable, value(default=0)
   ...
   Qualifier DESCRIPTION
             Default,
             Nonnegatable,
             Value(Required, List, Type = DECSRIPTION_WORDS)
             
As long I do not use the qualifier it's OK. I just do a CLI$Get_value
for each of them and get zeroes in return. But if I give the command:
    $ UTILITY/DESC=HEAD:3
the calls to CLI$Get_value for FOOT and PAGE return empty strings and
CLI$_ABSENT!
  OK, there at least two ways around this. I could split the qualiifier
into three, but I don't want to have too many qualifiers. That just
confuses the user, when he is reading the help text. And there are cases
when the workaround isn't possible. 
  The other way is to move the default values into the programme. But
I think that in this way you lose a bit of the idea of CDU. If I can keep
the default values to the CLD-file, I don't have to recompile and relink
to change them. Individual users might even have their own defaults if 
they have access to the command defintion.
  I haven't studied the manual carefully on this point, so I can't really
tell if it is a bug or a feature. But my personal opion is that is 
a bug and nothing more, and thus deserves an SPR. What do you think?

-- 
Erland Sommarskog       
ENEA Data, Stockholm    
sommar@enea.UUCP