On Thu, 1 Mar 2001 22:04:36 +0100, Rune wrote:
>On an unrelated note: Isn't there any way I can make the child macro handle
>and update a variable created in the mother macro, besides making the
>variable global? I'm afraid not?

I should probably read the docs more.  See the section called "Identifier
Name Collisions":

The complication comes when trying to assign a new value to an identifier 
at one level that was declared local at an earlier level. Suppose inside 
myinc.inc you do...

 #local D = 789;

If you are inside myinc.inc and you want to increment D by one, you might t
ry to do...

 #local D = D + 1;

but if you try to do that inside MyMacro you'll create a new D which is local 
to MyMacro and not the D which is external to MyMacro but local to myinc.inc. 
[actually, as you've noticed, this is an error.] Therefore you've said "create 
a MyMacro D from the value of myinc.inc's D plus one". That's probably not 
what you wanted. Instead you should do...

 #declare D = D + 1;

You might think this creates a new D that is global but it actually increments 
the myinc.inc version of D. Confusing isn't it?  Here are the rules:

1.) When referencing an identifier, you always get the most recent, most local 
version. By "referencing" we mean using the value of the identifier in a 
POV-Ray statement or using it on the right of an equals sign in either a 
#declare or #local.

2.) When declaring an identifier using the #local keyword, the identifier 
which is created or has a new value assigned, is ALWAYS created at the current 
nesting level of macros or include files.

3.) When declaring a NEW, NON-EXISTANT identifier using #declare, it is 
created as fully global. It is put in the symbol table of the main scene file.

4.) When ASSIGNING A VALUE TO AN EXISTING identifier using #declare, it 
assigns it to the most recent, most local version at the time.

In summary, #local always means "the current level", and #declare means 
"global" for new identifiers and "most recent" for existing identifiers.



-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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