lclint-interest message 188

From evs Wed Feb 11 13:09:56 1998
Date: Wed, 11 Feb 98 12:57:46 -0500
From: evs (David Evans)
To: 100566.1506@compuserve.com
Cc: lclint-interest@larch.lcs.mit.edu
In-Reply-To: Hermann Kleier's message of Wed, 11 Feb 1998 15:07:50 +0100 (CET) 
Subject: Constants in .lcl-files


Note that although the syntax of LCL is close to C, it is not the same,
and not everything that can be expressed in C can be expressed in LCL
(and vice versa).  This is probably more for historical reasons than any
real good reason.

> I used to have the following four definitions/declarations in a header file:
> 
> #define FAR
> #define RECORDSIZE 925
> typedef char FAR Inrecord [RECORDSIZE];
> typedef const char FAR *ConstString;
>
> The data types defined are used as function parameters.  Therefore I need to
> move the declarations to my .lcl-file.   But then the problems occurr:
>
> (1) FAR:           Just a macro defined to an emty string for reasonable
>                    operating systems. But some environments need to define `FAR'
>                    as `far'.

LCL files aren't run through a C pre-processor, so there is no way to
use macros like this in an LCL file.  If you really need to do something
like this, you could create a .pre-lcl file that gets run through a
preprocessor to produce a real .lcl file (however this is not
recommended).  

> (2) const:         Simply yields a parse error.  I know, the /*@*/ can guarantee
>                    that a function does not alter its parameters.  But a const
>                    data type is recognized by any ANSI-C compiler.

const is not supported by LCL.

> (3) RECORDSIZE:    I dislike to seed my constants around in the program.  I
>                    prefer macros or int constants.

In LCL, you can do,

	constant int RECORDSIZE;

> This approach is portable.  Unluckily this is not supported by ANSI-C.
> Instead ANSI-C offers the file , which can be used to typedef
> portable types.  I put the stuff in a global file named "ptypes.h", which I
> included in serveral projects over the years.
>
> How can I create types in a .lcl-file that depend on the contents of other
> files?

There's no way to do this, other than using a preprocessor on the LCL files.

Perhaps, some of these interface level details are better expressed in
.h files than using LCL, unless you are planning on writing detailed
specifications that use them.

--- Dave