julia> type Foo{T<:Number}
x::Vector{T}
end
julia> ops = [+, -, *, /]
4-element Array{Function,1}:
+
-
*
/
julia> syms = [symbol(op) for op in ops]
4-element Array{Any,1}:
:+
:-
:*
:/
julia> for sym in syms
dot_sym = symbol(".$sym") # create
element-wise symbol
docstr = "`$sym` also works for `Foo` types!" # this has to
be created before `@eval`
@eval begin
@doc $docstr -> # attach
docstring
function Base.$sym(a::Foo, b::Foo)
Foo($dot_sym(a.x, b.x)) # infix
notation wont work here!
end
end
end
julia> x = Foo([1,2,3])
Foo{Int64}([1,2,3])
julia> y = deepcopy(x)
Foo{Int64}([1,2,3])
julia> for op in ops
println("$x $op $y = $(op(x, y))")
end
Foo{Int64}([1,2,3]) + Foo{Int64}([1,2,3]) = Foo{Int64}([2,4,6])
Foo{Int64}([1,2,3]) - Foo{Int64}([1,2,3]) = Foo{Int64}([0,0,0])
Foo{Int64}([1,2,3]) * Foo{Int64}([1,2,3]) = Foo{Int64}([1,4,9])
Foo{Int64}([1,2,3]) / Foo{Int64}([1,2,3]) = Foo{Float64}([1.0,1.0,1.0])
help?> +
search: + .+
+(x, y...)
Addition operator. x+y+z+... calls this function with all arguments, i.e.
+(x, y, z, ...).
+ also works for Foo types!
julia>
El martes, 15 de diciembre de 2015, 10:28:53 (UTC-6), [email protected]
escribió:
>
> Hello,
>
> I have a type M and I would like to redefine all the operations *, +, -, /
> etc. over it. Since it would be everytime the same operations and since I
> want my code to be concise I thought about using a macro to define them,
> such as:
>
> type M
> a
> b
> end
>
> macro operator_obs(name)
> return quote
> function $name(m1::M, m2::M)
> return M($name(m1.a, m2.a), $name(m1.b, m2.b))
> end
> end
> end
>
> @operator_obs(+)
>
> m1 = M(2.0,3.0)
> m2 = M(4.0,5.0)
>
> +(m1, m2)
>
> But this doesn't seem to work. What did I do wrong?
>
> Many thanks,
>
