Hi Patrick, > In the "old" Clipper days we where told to NOT overuse PUBLIC or PRIVATE > variables because they consume lots of memory and are slow. How is this in > xHarbour? Is this still true?
I'd say, yes, because I don't think that xHarbour has changed the nature of PRIVATE and PUBLIC variables. Both are so called "dynamic variables" which are created at runtime, i.e. a symbol table holding symbolic names and values of these variables must be built at runtime. Lexical variables, like LOCAL and STATIC, are resolved at compile time. They are faster than dynamic variables, since the compiler can resolve their values to plain memory addresses. As a result, the lookup of values of lexical variables doesn't need a symbolic name table. > And, is a PUBLIC var more 'expensieve' than a PRIVATE var? No, both are equally expensive. The difference is that PUBLIC and PRIVATE variables are held in different symbol tables, as I assume. (Ron?) > Is it less 'expensive;' to have ONE public var with an array of lets say > 100 > elements or 100 separate public var's? Depends on how you define 'expensive'. When you want to reduce the size of the symbol table for PUBLIC variables, you go with one public variable holding an array of 100 elements. Drawback is speed: accessing an array element of a variable is slower than accessing the value stored in a variable (Memory optimization). When you want to reduce the access times to values held in memory, you go for 100 PUBLICs and grow the symbol table (Speed optimization). IMO, neither memory nor speed optimizations are limiting factors in today's application development. The question is, how to organize 100 or 10000 different variables so that a programmer can address them; not during compile time or runtime, but during programming time. The optimal replacement for PUBLIC variables with xHarbour is IMO one GLOBAL variable holding a Hashtable that stores names/values of former PUBLIC variables. My 2cnts, -- Hannes ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ xHarbour-developers mailing list xHarbour-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xharbour-developers
