Alos, as Mauro said, instead of manually creating the functors, packages like FastAnonymous.jl makes it easier for you.
On Wednesday, June 17, 2015 at 10:11:22 PM UTC+2, Kristoffer Carlsson wrote: > > You could also use something called functors which basically are types > that overload the call function. When you pass these as argument the > compiler can specialize the function on the type of the functor and thus > inline the call. See here for example for them being used effectively for > performance increase: https://github.com/JuliaLang/julia/pull/11685 > > As an example I took the code for insertionsort and made it instead accept > an argument f which will be the functor. I then create some functors to > sort on the different type fields and show an example how sort is called. > > > function sort!(v::AbstractVector, f, lo::Int=1, hi::Int=length(v)) > @inbounds for i = lo+1:hi > j = i > x = v[i] > while j > lo > if f(x, v[j-1]) > v[j] = v[j-1] > j -= 1 > continue > end > break > end > v[j] = x > end > return v > end > > # Some type > immutable CompType > a::Int > b::Int > c::Int > end > > > b = [CompType(1,2,3), CompType(3,2,1), CompType(2,1,3)] > > # Functors > immutable AFunc end > call(::AFunc, x, y) = x.a < y.a > immutable BFunc end > call(::BFunc, x, y) = x.b < y.b > immutable CFunc end > call(::CFunc, x, y) = x.c < y.c > > # Can now sort with good performance > sort!(b, AFunc()) > println(b) > sort!(b, BFunc()) > println(b) > sort!(b, CFunc()) > println(b) > > > Now, this is of course not optimal to rip code out of base. It would be > better if we could pass a functor straight to Base.sort!. > > > On Wednesday, June 17, 2015 at 8:13:41 PM UTC+2, Ben Ward wrote: >> >> Hi, I want to create a macro with which I can create a function with a >> custom bit of code: >> >> In the repl I can do a toy example: >> >> >> *name = :hi* >> >> >> *vectype = Vector{Int}* >> >> >> *quote** function ($name)(v::$vectype)* >> >> *println("hi")* >> >> *end* >> >> *end* >> >> However if I try to put this in a macro and use it I get an error: >> >> *macro customFun(vectype::DataType, name::Symbol)* >> >> >> * quote** function ($name)(v::$vectype)* >> >> * println("hi World!")* >> >> * end* >> >> * end* >> >> >> >> *end* >> >> *@customFun(Vector{Int}, :hi)* >> >> What am I doing wrong? I'd like to use macro arguments to provide a >> function's name, and the datatype of the argument. I haven't used macros to >> define functions more complex than simple one liners. >> >> Thanks, >> Ben. >> >
