How Do I ......????

[Kurt Wall]

On Thu, Sep 09, 2004 at 02:08:49PM -0500, Ben Duncan took 69 lines to write:
> 
> Ok, I am writing a system that contains several modules.
> 
> The header for the system has a declaration for a function defined
> as :
> 
> int OpenWindow( int row, int col, int rowsize, int colsize, const char 
> *title)
> 
> row, col, rowsize, colsize are USED thru out all the modules.
> 
> I have one program called slag-module.c, that forms the library core
> and calls all other modules compiled in. Some of the modules are
> called : grid.c, button.c, form.c, checkbox.c, ..etc..etc..

They each include the header, right?

> So, I have a compile statement that looks like thus:
> ------------------------------------------------------
> for file in `ls src/*.c`
> do
>  OBJ=`basename $file ".c"`
>  echo "Now creating file $OBJ from $file "
>  cc -c -O2 -fno-strength-reduce " objdir/${OBJ}.o \
>    -I./include -I/usr/include/slang \
>        -fwritable-strings \
>        src/${OBJ}.c
> done

That's certainly doing it the hard way. Make is your friend:

OBJS := grid.o button.o form.o checkbox.o
CFLAGS := -O2 -fno-strength-reduce -fwritable-strings
INCLUDES := -I./include -I/usr/include/slang

.c.o:
	$(CC) -c $(CFLAGS) $(INCLUDES) -o objdir/$@ $<

> echo "Now creating the .so module"
> cc -c -02 -fno-strength-reduce  -shared -fPIC \
>   -I./include -I/usr/include/slang src/slag-module.c  \
>        objdir/*.o \
>        -o objdir/slag-module.so \
>        -L/usr/lib -lslang -ldl -lm
> --------------------------------------------------------
> 
> In the slag-module.c is the actual OpenWindow function, and
> in several of the c program modules they call
>   OpenWindow( 'int row', 'int col', 'int rowsize', 'int colsize',  "String 
>   of data")

Why not just use a proper function? And why are are you specifying
multi-character char types? 

OpenWindow(1, 2, 3, 4, "some string");

> What I would like to do is set up some sort of GLOBAL variable, so that the
> modules that are using "OpenWindow" would do it this way:
> 
> gl_row = 'int row' ;
> gl_col = 'int col' ;
> gl_rowsize = 'int rowsize' ;
> gl_colsize = 'int colzise' ;
> 
> OpenWindow( "string of data")
> 
> An where "gl_xxxxx" is modifiable from any modules, they are
> defined JUST in one place.

You just write a wrapper around OpenWindow() that calls it the way you
want it called:

OpenWindowWrapper(const char *s)
{
	OpenWindow(row_val, col_val, rowsize_val, colsize_val, s);
}

More generally, unless I'm missing something, it is unwise program design
to do what you're proposing. It defeats type checking and makes your code
a lot harder to read. Those global variables can get changed by anything
in scope, which introduces some nasty bugs. 

> So, how do I set this up do to this ?

Kurt
-- 
No man in the world has more courage than the man who can stop after
eating one peanut.
	-- Channing Pollock