Re: gEDA-user: Problem compiling gnetman . . . .

[Bill Cox <bill@viasic.com>]

Hi, Stuart.

Stuart Brorson wrote:
...

> I checked it out, and it turns out that the problem is the UTINT
> declaration in:
>
> static char *readLine(void)
> {
>    schLineLength = 0;
>    UTINT c;
> [. . . . etc . . . .]
>  
This is due to a new enhancement in gcc.  The error isn't the UTINT 
(it's used 12 lines earlier without error).  The problem is that 
schLineLength = 0 is a statement, not a declaration.  In ANSI C 2.0, the 
declaration of c is illegal after any statements.  In C99, this is 
legal, and gcc recently adopted this.  It's been causing some problems 
at work, since some of our programmers have older compilers.

I feel strongly about making code portable, and this code currently 
isn't.  I'll look into getting the compiler to at least print a warning 
about this rule, and I'll upload another version.

There's nothing about CVS that makes code read-only.  In fact, the tar 
archive should have left everything writable, so the problems editing 
the file I don't understand.  It's really kind of weird.

As for the include chain, you'll find that the code follows very strict 
rules, and has an extensive coding methodolgy behind it.  One of the 
primary goals behind the methodology is code clarity, and I suspect 
you'll generally find the code easy to read.  Unfortuneatly, the 
metholodology has never been documented in the public domain, even 
though DataDraw is opensource.

I don't know if you really wanted to hear the whole data dump for 
include chains, but here it is.  Feel free to skip the rest of this 
message if it's not of interest.

For header files, the coding methodoloy uses the following rules:

-- The OS portability layer is the util module.  Util.h includes various 
aspects of this, including uttypes.h.  User code may directly include 
util.h, but not the other ut<name>.h files.  Generated code also 
publicly includes util.h, so when including a generated header file 
(files of the form xxxddr.h), don't bother including util.h at all.
-- User modules generally fall into two types:
   1 - databases, like the database directory.  These modules put both 
their generated header files (dbddr.h), and user-defined header file 
(db.h) in the include directory.  That allows all the internals to be 
accessed by tools using the database
   2 - tools, like the schematic reader, or spice netlist writer. 
These modules put the generated header file (like schddr.h) in the 
local module directory.  The module's user-defined header file (like 
sch.h) is also in the local directory.  Tools generally have an external 
interface, which is a header file of the form xxxext.h, like schext.h. 
These external header files are put into the include directory, and are 
included by the tool's local header file.
-- With some exceptions, files within a module include only the module's 
internal header file, like sch.h.  Exceptions are:
   1 - Files may include standard library header files, like stdio.h
   2 - Files may include other module's external header file only if 
they are top level control modules, such as the main loop, or the guile 
interface.
   3 - Anything goes in the GUI.  No rules apply there.  Can you tell 
that we aren't very good at developing GUI's?
-- To help DataDraw understand externally typedefed types, files of the 
form xxxtypedef.h are written by hand.  They only exist if the user has 
defined an external typedef in a given tool with the DataDraw schema editor.

The include methodology eliminates the need for the #ifdef wrappers 
around include files to avoid including a header file twice.  It also 
protects a modules internals from another module.

We may want to take this discussion off the geda-user message board.  My 
direct e-mail is bill@viasic.com.

Bill