Question

Simple question:

I really like the idea of encapsulation, but I really don’t know if it is worth it is a performance critical situation.

For example:

x->var;

is faster than

x->getVar();

because of the function calling overhead. Is there any solution that is both fast AND encapsulated?

Answer 1

• “There’s no overhead if the getVar function is inlined”
• “If getVar() is simply return var; and is inline and non-virtual the two expressions should be optimized to the same thing”
• “getVar() in all possibility could be inlined”

Can Mr Rafferty make the assumption that the code will be inlined? Not “should be” or “could be”. In my opinion that’s a problem with C++: it’s not especially WYSIWYG: you can’t be sure what code it will generate. Sure there are benefits to using oo but if execution efficiency (performance) is important C++ (or C# or Java) is not the obvious choice.

On another topic

There’s a lot of talk about “Premature Optimization” being the root of all evil and, since no one gets what the premature is about a lot of programmers think that optimization is the root of all evil.

In these cases I find it helpful to bring out the original quote so everyone may see what they’ve been missing (not to say misunderstanding and misquoting):

“We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.”

Most people attribute the quote to Tony Hoare (father of QuickSort) and some to Donald Knuth (Art of Computer Programming).

An informative discussion as to what the quote may or may not mean may be found here: http://ubiquity.acm.org/article.cfm?id=1513451