I thought I'd share this little piece of code:

--- %< snip %< ---
#include "strings.inc"

#macro IFDEF(Name)                                                   	
	#local Test = concat("defined(",Name,")?yes:no");
	(Parse_String(Test))
#end

#macro Set_Default_Value(_Name,_Value)
	#if (!IFDEF(_Name))		
		#declare _Set_Default_Value_Temporary = _Value;
		Parse_String(concat("#declare ",_Name," = _Set_Default_Value_Temporary;"))
		#undef _Set_Default_Value_Temporary
	#end
#end
--- %< snap %< ---

Using the second macro, you can set a default value for identifiers, 
even if they do not exist, i.e. it's an replacement for the following 
construct:

#ifndef (_Name) #declare _Name = _Value; #end

is the same as

Set_Default_Value("_Name",_Value);

(Please note the "" around the identifier's name!).

This does not really reduce the amount of typing or something like that, 
but I like it because it's more readable (IMHO) and it's only meant to 
be an illustration for similar, but more complicated macros.

BTW: The first macro can be used to check if an identifier whose name is 
the content of the given string is defined, e.g.

#if (IFDEF("my_first_identifier"))
	#debug "It does exist\n"
#end

Again, not really helpful for "standard" scenes, but very nice if you're 
doing lots of things with Parse_String (which is propably the most 
powerfull macro I've ever seen in SDL :)


HTH,
Florian
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