Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!world!burley
From: burley@world.std.com (James C Burley)
Newsgroups: comp.lang.fortran
Subject: Re: passing DIMs via COMMON??
Message-ID: <BURLEY.90Oct11030305@world.std.com>
Date: 11 Oct 90 07:03:05 GMT
References: <MARTIN.90Oct9111140@slsiris.harvard.edu>
Sender: burley@world.std.com (James C Burley)
Distribution: comp
Organization: The World
Lines: 54
In-Reply-To: martin@slsiris.harvard.edu's message of 9 Oct 90 15:11:40 GMT

In article <MARTIN.90Oct9111140@slsiris.harvard.edu> martin@slsiris.harvard.edu (Mr. Science) writes:

   Ive noticed that when I try to specify LUNs or adjustable array
   parameters by passing the value in a common block, f77 doesnt know
   what to do.  For example, I want to specify all "magic numbers" 
   (LUNs, array DIMs...) in the main program section to simplify code 
   maintenance.  If I try to pass array dimensions via a common block, the
   compiler complains about an "adjustable array dimension error";
   if I pass these values in the subroutine call, however, the program
   executes as expected.  To simplify the code, I would prefer not
   passing these values for each subroutine call.   

   ....................................................................
   Patrick Martin
   Martin@SLSVAX.Harvard.Edu
   Martin@SLSIRIS.Harvard.Edu

   Disclaimer: I get taxed too high to afford an opinion.
   ....................................................................

Could you post a reduced example of what you're trying to do with LUNs or
arrays that isn't working?  Meanwhile, I tried sending you an answer twice
but some mail daemon rejected it, so here is my attempt to address the
array issue:

Make sure you are passing the arrays themselves as dummies; you can
not put adjustable arrays in common areas.

However, if you are doing this right, and the compiler accepts a subroutine
whose dummy arguments include not only an adjustable array but all the
variables that dimension the array, but does not accept a subroutine
where some or all of the variables that dimension a dummy array are in
a common area known to the subroutine, then I think the compiler is
broken.

I.e. you should be able to do both

    SUBROUTINE X(A,N)
    INTEGER A(N)
    ...

and

    SUBROUTINE X(A)
    INTEGER A(N)
    COMMON /FOO/N
    ...

This is, I believe, standard for ANSI 77.

Whether a particular implementation (such as f77) supports it is another
issue!

James Craig Burley, Software Craftsperson    burley@world.std.com