Anyone come up with some cool algorithms/templates for D lately?

In the past people have posted these cool algorithms/templates they figured out how to do in some neat way with D. Things like wow, this would take INF+ lines in C++ but I can do it in 2 in D. This seems to have died down a bit. I always found these topics most interesting. So I'm requesting people to post "cool stuff" they figured out how to do in D. -Joel

I'd expect interesting topics with a new release. Have you noticed; it's been the longest wait since at least a year. > So I'm requesting people to post "cool stuff" they figured out how to do in D. > > -Joel

You're right, but still: the last release introduced struct destructors, which have been requested a couple of times (mostly C++ folk, probably) and I, too, am eagerly awaiting cool code making use of struct destructors. L. "Saaa" <empty@needmail.com> wrote in message news:fu93d0$1cfh$1@digitalmars.com... > I'd expect interesting topics with a new release. > Have you noticed; it's been the longest wait since at least a year. > > >> So I'm requesting people to post "cool stuff" they figured out how to do in D. >> >> -Joel > >

Psst -- don't tell anyone but ... opDot... coming to a DMD near you soon. --bb Lionello Lunesu wrote: > You're right, but still: the last release introduced struct destructors, which have been requested a couple of times (mostly C++ folk, probably) and I, too, am eagerly awaiting cool code making use of struct destructors. > > L. > > > "Saaa" <empty@needmail.com> wrote in message news:fu93d0$1cfh$1@digitalmars.com... >> I'd expect interesting topics with a new release. >> Have you noticed; it's been the longest wait since at least a year. >> >> >>> So I'm requesting people to post "cool stuff" they figured out how to do in D.

janderson wrote: > In the past people have posted these cool algorithms/templates they figured out how to do in some neat way with D. Things like wow, this would take INF+ lines in C++ but I can do it in 2 in D. This seems to have died down a bit. I always found these topics most interesting. > > So I'm requesting people to post "cool stuff" they figured out how to do in D. I'm still flabbergasted by the cool things you can do inside fixed-length matrix/vector templates. For instance (this is all from my matrix/vector classes in OpenMesh/D which are basically a complete rewrite of the original C++ versions) struct MatrixT(T, int M, int N) { alias T Scalar; union { Scalar[M*N] values_ = void; static if(M<=10 && N<=10) { mixin(_gen_elements!(M,N)("Scalar")); } } } // Generate the elements m00,m01,m02... elements // For matrices with dimensions < 10 x 10 only. private string _gen_elements(int M, int N)(string type) { static assert(M<=10); static assert(N<=10); char[] Num = "0123456789"; string ret; for(int col=0; col<N; ++col) { ret ~= type ~ " "; for (int row=0; row<M; row++) { ret ~= "m" ~ Num[row] ~ Num[col]; if (row!=M-1) ret ~= ", "; } ret ~= ";\n"; } return ret; } This creates aliases to each element of the matrix of the form m00, m01, m02, but only if the matrix is small enough. I have no idea how you'd do that in C++. I don't think it's really possible. Here's another -- generating the unrolled code for multiplying two matrices together: /// Multiply MxN matrix time NxP matrix void mat_mult_ret(T,int M,int N,int P)( /*const*/ref MatrixT!(T,M,N) A, /*const*/ref MatrixT!(T,N,P) B, inout MatrixT!(T,M,P) ret) { with(ret) { mixin(_gen_mat_mult_body!(M,N,P)("A","B")); } } private string _gen_mat_mult_body(int M, int N, int P)(string A, string B) { string ret; for (int row=0; row<M; ++row) { for(int col=0; col<P; ++col) { ret ~= " "; ret ~= "values_["~ctfe_itoa(col*M+row)~"] = "; for(int jj; jj<N; ++jj) { string JJ = ctfe_itoa(jj); string iA = ctfe_itoa( row+jj *M ); string iB = ctfe_itoa( jj +col*N ); ret ~= A ~ ".values_["~iA~"]*"~B~".values_["~iB~"]"; if (jj != N-1) { ret ~= " + "; } else { ret ~= ";\n"; } } } ret ~= "\n"; } return ret; } Wow. The code generating function basically just looks like a standard triply-nested matrix multiply, but instead of doing multiplies it just splits out code that implements multiplies. I think that's pretty sweet. --bb

Reply to janderson, > In the past people have posted these cool algorithms/templates they > figured out how to do in some neat way with D. Things like wow, this > would take INF+ lines in C++ but I can do it in 2 in D. This seems > to have died down a bit. I always found these topics most > interesting. > > So I'm requesting people to post "cool stuff" they figured out how to > do in D. > > -Joel > // Sort data using keys as the order uint[] keys, data; assert(keys.length == data.length); ulong[] arr; arr.length = keys.length; foreach(int i, uint _; keys) arr[i] = (cast(uint)keys[i])<<32 | data[i]; arr.sort; foreach(int i, uint _; keys) data[i] = cast(uint)(arr & 0x0ffff_ffff);