[julia-users] Re: Supertypes in function arguments
Hello Linus,
This is based on how array types are defined. In general, Vector{subtype}
is not a subtype of Vector{supertype}.
Try this:
f{R:Real}(x::Array{R}) = x
-Tim
On Friday, June 26, 2015 at 8:38:12 AM UTC-7, Linus Härenstam-Nielsen wrote:
I ran into a problem with types today that I don't know how to interpret.
If I define a function according to
f(x::Real) = x
it returns x as expected as long as the type of x is a subtype of Real.
However if I define
f(x::Array{Real}) = x
it throws MethodError no matter what I pass as argument. For example when
I try to pass it an Int array:
f([1 2 3; 3 4 5])
ERROR: MethodError: `f` has no method matching f(::Array{Int64,2})
I would expect it to work like
f{T:Real}(x::Array{T}) = x
and accept any array of reals. Am I missing something?
[julia-users] Re: Supertypes in function arguments
Ok, that makes sense. In that case what would be the best way to write a
funcion that accepts several Real arrays (of not necessarily the same
type)? Currently I'm using
function f{T1,T2,T3 : Real}(x::Array{T1}, y::Array{T2}, z::Array{T3})
...
end
But that gets messy very quickly if there are many arguments.
On Friday, June 26, 2015 at 6:00:25 PM UTC+2, Tim Wheeler wrote:
Hello Linus,
This is based on how array types are defined. In general, Vector{subtype}
is not a subtype of Vector{supertype}.
Try this:
f{R:Real}(x::Array{R}) = x
-Tim
On Friday, June 26, 2015 at 8:38:12 AM UTC-7, Linus Härenstam-Nielsen
wrote:
I ran into a problem with types today that I don't know how to interpret.
If I define a function according to
f(x::Real) = x
it returns x as expected as long as the type of x is a subtype of Real.
However if I define
f(x::Array{Real}) = x
it throws MethodError no matter what I pass as argument. For example when
I try to pass it an Int array:
f([1 2 3; 3 4 5])
ERROR: MethodError: `f` has no method matching f(::Array{Int64,2})
I would expect it to work like
f{T:Real}(x::Array{T}) = x
and accept any array of reals. Am I missing something?
[julia-users] Re: Supertypes in function arguments
I've seen a discussion on this somewhere... here it is:
https://github.com/JuliaLang/julia/issues/6984, and there's more discussion
at https://groups.google.com/forum/#!topic/julia-users/alavN8tRdyI
No built-in solution so far from what I can see, although following the
first post there, you could define a type alias for an array that has
elements that are all the same Real subtype:
typealias RealArray{R:Real} Array{R}
function f(x::RealArray, y::RealArray, z::RealArray) ...
On Friday, 26 June 2015 17:46:22 UTC+1, Linus Härenstam-Nielsen wrote:
Ok, that makes sense. In that case what would be the best way to write a
funcion that accepts several Real arrays (of not necessarily the same
type)? Currently I'm using
function f{T1,T2,T3 : Real}(x::Array{T1}, y::Array{T2}, z::Array{T3})
...
end
But that gets messy very quickly if there are many arguments.
On Friday, June 26, 2015 at 6:00:25 PM UTC+2, Tim Wheeler wrote:
Hello Linus,
This is based on how array types are defined. In general, Vector{subtype}
is not a subtype of Vector{supertype}.
Try this:
f{R:Real}(x::Array{R}) = x
-Tim
On Friday, June 26, 2015 at 8:38:12 AM UTC-7, Linus Härenstam-Nielsen
wrote:
I ran into a problem with types today that I don't know how to interpret.
If I define a function according to
f(x::Real) = x
it returns x as expected as long as the type of x is a subtype of Real.
However if I define
f(x::Array{Real}) = x
it throws MethodError no matter what I pass as argument. For example
when I try to pass it an Int array:
f([1 2 3; 3 4 5])
ERROR: MethodError: `f` has no method matching f(::Array{Int64,2})
I would expect it to work like
f{T:Real}(x::Array{T}) = x
and accept any array of reals. Am I missing something?
