Hey guys! I'm not very familiar with boost.mpl, or boost.preprocessor, so I wanted to ask. I've written a compile-time hash function. Here's an example that uses it:- #include <iostream> using namespace std; //Compile-time hasher. #define HASH(partial,c) (((partial) << 1) ^ (c)) #define HASH_1(p1) HASH(0,(p1)) #define HASH_2(p1,p2) HASH(HASH_1(p1),(p2)) #define HASH_3(p1,p2,p3) HASH(HASH_2(p1,p2),(p3)) #define HASH_4(p1,p2,p3,p4) HASH(HASH_3(p1,p2,p3),(p4)) #define HASH_5(p1,p2,p3,p4,p5) HASH(HASH_4(p1,p2,p3,p4),(p5)) #define HASH_6(p1,p2,p3,p4,p5,p6) HASH(HASH_5(p1,p2,p3,p4,p5),(p6)) #define HASH_7(p1,p2,p3,p4,p5,p6,p7) HASH(HASH_6(p1,p2,p3,p4,p5,p6),(p7)) #define HASH_8(p1,p2,p3,p4,p5,p6,p7,p8) HASH(HASH_7(p1,p2,p3,p4,p5,p6,p7),(p8)) #define HASH_9(p1,p2,p3,p4,p5,p6,p7,p8,p9) HASH(HASH_8(p1,p2,p3,p4,p5,p6,p7,p8),(p9)) #define HASH_10(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10) HASH(HASH_9(p1,p2,p3,p4,p5,p6,p7,p8,p9),(p10)) #define HASH_11(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11) HASH(HASH_10(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10),(p11)) #define HASH_12(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12) HASH(HASH_11(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11),(p12)) #define HASH_13(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13) HASH(HASH_12(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12),(p13)) #define HASH_14(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14) HASH(HASH_13(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13),(p14)) #define HASH_15(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15) HASH(HASH_14(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14),(p15)) #define HASH_16(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15,p16) HASH(HASH_15(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p11,p12,p13,p14,p15),(p16)) /* .. omitted the rest, but it's there till around HASH_30 .. */ //Runtime hasher. unsigned int hash(char const *p) { unsigned partial = 0; while (*p) { partial <<= 1; partial ^= *p; ++p; } return partial; } //Test it in a main() int main() { char str[31] = "thisisatest"; //Yay! Switch on strings! switch (hash(str)) { case HASH_11('t','h','i','s','i','s','a','t','e','s','t'): cout << "You said, 'this is a test'!"; break; case HASH_16('y','e','t','a','n','o','t','h','e','r','s','t','r','i','n','g'): cout << "You said, 'yet another string'!"; break; } return 0; } So, I was wondering how I could use boost.preprocessor to be able to write a more generic hash function, something like HASH_GENERIC(mystring), or at least HASH_GENERIC(8,mystring). BTW, here's a vim script that changes any thing like '@something@' on the curent line into "HASH_9('s','o','m','e','t','h','i','n','g')", when you type ',h':- map ,h :s/@\(.\+\)@/\='HASH_'.strlen(submatch(1))."('".join(split(submatch(1), '\zs'), "','")."')"/<CR> ;-) -- Nikhilesh S http://nikki.drupalsite.org