Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!husc6!tut.cis.ohio-state.edu!mailrus!umix!uunet!mcvax!enea!sommar
From: sommar@enea.se (Erland Sommarskog)
Newsgroups: comp.os.vms
Subject: Re: Help us defend against VMS!
Keywords: Wild cards
Message-ID: <2918@enea.se>
Date: 26 Mar 88 17:23:28 GMT
References: <1782@pasteur.Berkeley.Edu>
Reply-To: sommar@enea.UUCP(Erland Sommarskog)
Followup-To: comp.os.vms
Organization: ENEA DATA AB, Sweden
Lines: 47

Off we go again. Some quibblings about wild cards this time. And 
if you feel you had enough of this already, well the form feed it's
for you.

>A more annoying <...> is DCL's silly treatment of *.  Leaves
>interpretation of the damn thing up to the command.  So some do, some
>don't.  And the ones you want 'em to, don't.  E.g., the infamous SET DEF:
>...
>Well, so, there's this lib$find_file or similar routine that your program
>can use, that will parse filenames iteratively, giving you back one per
>call.  And your users have stood outside your office with cut-down

First we discussed command parsing. DCL parses the command and inkoves
the image. In Unix the program has to parse them itself, giving a non-
uniform interface. With wild cards it's the opposite. The shell expands
them, whereas DCL leaves that to the program and the file system. 

The good way with the Unix style is that it's easy to write a utility
that operates on a suite of files. Just read argv to the end. This is 
harder under VMS. LIB$Find_file (or $parse and $search) are more difficult
for the unexperiencd user. 

The VMS way has two advanteges. Unix assumes that all arguments are files.
This is often, but not always true. "HELP *" does also give a better result
than "man *". The other point is that you use file specification in more
places than the command line interpreter. Instead of putting the file- 
name parsing in DCL, VMS provides routines (in RMS) for a uniform 
behaviour. Not only wild cards, but also logical names, related names 
and defaults. But of course, the programs must actually use them, 
for it all to work. I assume Unix has *something* similar to this -
it ought to have - but ~-substitution does not always work, as translation
of environment variables. (Which is the closest to logical names Unix 
comes as far as I know.)

And for postorder/preorder of DELETE: DELETE uses the same routines as
all the other commands, in which we would prefer preorder. No problem
for "rm" to make it right. It has to do the traversal itself anyway.
Unix doesn't provide a wild card like "...". At least no one has told
me about it.




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