Author: Gerd Isenberg
Date: 11:00:37 07/29/03
Go up one level in this thread
On July 29, 2003 at 13:31:29, Dieter Buerssner wrote:
>On July 29, 2003 at 01:54:29, Gerd Isenberg wrote:
>
>>On July 28, 2003 at 19:00:41, Dieter Buerssner wrote:
>
>>i see your point - i have no problems with references, may be due to Java.
>>References are very intuitive for me, but i don't use them "randomly" in
>>functions.
>>Most often the "output" paramter by reference is the first (left) one - and i
>>use appropriate function identifiers, implying the desired side effect.
>>
>> int bitScanAndReset(BitBoard &bb);
>> void assignWithMask(int &target, int source, int mask);
>
>I would probably use
>
> int assignWithMask(int source, int mask);
>
>which also has the advantage, that it can be used in nested function calls.
Hi Dieter,
i agree, but target is a "right" value too in the expression:
target = target ^ ((source^target) & mask);
therefore a third parameter is necessary
int assignWithMask(int target, int source, int mask);
But that is what Uri wan't to avoid, using target twice.
>
>>>It may even be a performance issue. I read your suggestion about the small
>>>inline functions vs. macros. I basically agree. But when using reference
>>>paramaters (your example did), things might be very different. This might make
>>>it very difficult or even impossible to make a good optimization for the
>>>compiler.
>>
>>I never found a problem so far. I guess from compilers point of view, there is
>>no pragmatical difference between a pointer and a reference.
>
>I remember at least one case, where the macro was faster, than a function call
>with a pointer parameter (actually, most probably the function had 2 outputs at
>least). I don't have the case handy, but looking over my macros, I might find it
>again. Perhaps the following rather constructed example can show the point:
>
>extern unsigned or_tbl[], and_tbl[]; /* non const */
>
>void foo(unsigned *ap, unsigned idx)
>{
> /* Of course, one could write it in one line */
> *ap &= and_tbl[idx];
> *ap |= or_tbl[idx];
>}
Yes, that may happen, but i don't like macros soo much due to the known reasons.
My point was pointer versus reference rather than inlined versus macro ;-)
Cheers,
Gerd
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