[oclug] programming style vs performance

[Olaf Baumann]

Consider the following two snippets of functionally equivalent 
fictional code

1)
int doSomething() {
   int argOne = getArgOne();
   int argTwo = createSomethingForTheSecondArgument();
   int argThree = 3 * 4 * SOME_CONSTANT;
   long result = doSomethingElse( argOne, argTwo, argThree);
   return result;
}

2)
int doSomething() {
   return result = doSomethingElse(getArgOne(), 
createSomethingForTheSecondArgument(), 3 * 4 * SOME_CONSTANT);
}


Which would you prefer?

When I can, I try to write my code for the next programmer that has to 
understand/modify it.  Personally, I would much rather work on code 
like listing 1.  If needed, debugging code like listing 2 gets 
difficult as there is no line or local variables whose state can be 
viewed.  Also, adding application logging to listing 2 would be 
impossible or worse, if the methods called had side effects.

Is it possible that a compiler would produce faster code from listing 2 
(having fewer /named/ local variables on the stack)?  Or would any 
compiler worth its salt optimize both to the same result.  Not that I'm 
one to fall into the trap of premature optimization, but I would like 
to be aware of the possibilities.

I've tried to keep the code mostly language-independent as answers may 
be language-specific and the differences between languages would be 
interesting to see.  For example, I would guess that if this code was 
interpreted python (without any compilation stage), it would be slower 
if for no other reason, there are more characters in the source to 
scan.

-- 
Olaf