Author: José Carlos
Date: 06:26:22 01/22/03
Go up one level in this thread
On January 21, 2003 at 14:04:20, David Rasmussen wrote:
>On January 21, 2003 at 12:08:08, Uri Blass wrote:
>
>>I finished the time of my evaluation of checking bounds.
>>
>
>What is "checking bounds"? Where can I download that?
>
>There are many boundscheckers available. Valgrind is free.
>
>>I talk about it with other programmers(not of chess programs and not in C).
>>
>>They suggested the following ideas:
>>1)Not many people buy checking bounds and this is the reason that the price is
>>so high.
>>2)checking bounds may be effective to check some work of other programmers but
>>programmers who work about their program do not need it.
>>
>>
>>They suggested that it is better if I write functions to do it and replace all
>>A[i]= with some f(A,i) that will also check for me if i is inside the bounds
>>that are defined by A.
>>I said that I think that if I do it then my code will be at least twice slower.
>>
>
>I was about to suggest the same thing, although in C++, where you have the
>immense benefit of uniform interfaces of such things. So you can make a
>boundschecked array that you use in debug builds and a normal array or whatevery
>you want, in release builds. All you do is change one line when you want bounds
>checking. That's the way I do it. I just define whether it's a release or a
>debug build, and the debug build is slow and safe, the release build is fast and
>also safe (if the debug build was). This kind of thing comes natural in C++,
>even if you use C++ only as a better C, that is, you (almost) only use the C
>constructs of C++. If I had to do the same thing in C, it would be much harder
>and would involce ugly #define macros that do not obey scope or type rules etc.
>Bottom line: Less headache, fewer bugs, faster development, as fast or faster
>program. This kind of thing can be done for a lot more things (and more complex
>ones) than bounds checking. It can in general be used to secure the sanity of
>all your data.
No need for "ugly" defines in C; no performance loss:
inline TPiece GetBoardSquare(int sq)
{
assert(sq >= 0 && sq < 64);
return(Board[sq]);
}
inline SetBoardSquare(int sq,TPiece piece)
{
assert(sq >= 0 && sq < 64);
assert(piece_is_a_legal_value);
Board[sq] = piece;
}
Asserts only compile in debug mode. You don't _need_ C++ to write good code.
José C.
>>I can also do a special slower code for debug(something that I do not do today)
>>but I do not like the idea that every time that I add code then I will need to
>>add also code for debugging.
>>This may also make me slower in finding specific place that I want to change.
>>
>
>In C++ you would once and for all define a boundschecked array type that was
>interchangable with a normal array for release builds (same interface). You do
>it once, you use it 10000000 times for the rest of your life, and you safe money
>for boundscheckers.
>
>>1)Did checking bounds help you?
>
>Yes.
>
>>2)Do you usually add code for debugging inspite of having checking bounds?
>
>Yes, because there are lot other bugs than bounds bugs.
>
>>If 1 and 2 are positive then question 3
>>
>>3)Do you decide to use less debugging code thanks to checking bounds?
>>
>
>No. Correctness is extremely important to me.
>
>/David
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.