[Bf-committers] Casting arrays (matrices)

Douglas Toltzman bf-committers@blender.org
Wed, 2 Jul 2003 17:01:06 -0400 (EDT)

I'm with Maarten on this one.  If I gave you a prototype for a string copy
function that read "strcyp(char *target,const char *source)" it would not
only tell you that your source string wouldn't be modified, but it would
allow the compiler to enforce that behavior.

The "const" modifier is a great documentation feature, at the very
minimum, and provides an additional level of protection from coding errors
at best.  Incidentally, it also helps the optimizer.

On Wed, 2 Jul 2003, Maarten Gribnau wrote:

> Hi Ton
> > Reading the arithb.c code, I found that someone (NaN) has included a 
> > lot of 'const' variables in the function declarations. I have 
> > absolutely no clue what it's good for. Originally, the code worked 
> > fine without, as still is in the MTC_matrixops.c version in 
> > source/blender/blenlib/
> >
> > I've removed the 'const' everywhere from arithb.c. The code compiles 
> > quite a lot faster, with only a few and more useful warnings left.
> How does the const cause trouble?
> The const is actually useful. It tells you the function is not going to 
> modify the variable (usually pointers and references in C++) passed to 
> it. It makes the variable an "in only" variable.
> Maarten