"Christian Froeschlin" <chr### [at] chrfrde> wrote in message 
news:4a40e339$1@news.povray.org...
> ...  note that macros can have parameters and do not
> need to use global variables. From a software engineering view that
> would be preferred because it avoids conflicts with other macros
> or variable names you wish to use for something else

I ceratinly agree that in many programming languages, other approaches would 
be preferable, but POV-Ray is a bit limited in this respect and the use of 
global variables to control macros that require large numbers of controls is 
the best approach I've been able to come up with in POV-Ray from a software 
engineering perspective.

The main advantage with using variables in this way is that you can specify 
just the variables you need, whereas to accommodate all desired permutations 
using the 'MacroA, MacroB etc' technique could require thousands of wrapper 
macros.

In this instance, to parameterise drawers, doors, door-handles, the cabinet 
itself, shelves, kickboards and worktops, each with an average of 6 
parameters for dimensions, colors, openness, handedness etc, you could 
pretty quickly get up to 40 or 50 settings, which, IMO, becomes difficult 
and messy to manage with parameters. OTOH, in this particular case, if the 
macro call is always to be written by an external application then I admit 
that this could still be viable.

With the object collection it was also discovered that the use of local 
variables didn't guarantee you won't get naming collisions, because certain 
identifiers always have a global context, whereas adhering to simple naming 
standards, for both local and global variables, seem to readily avoid all 
those sorts of problems.

Regards,
Chris B.

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