ERROR: UndefVarError: T not defined / Weird Method Parameter Problem

General Usage
1 
abstract type Fun{T,R} <: Function end

struct TypedFun{T<:Tuple,R} <: Fun{T,R}
   fn::Function
end

function test(fun::Fun{Tuple{T},Vector{CV} where CV<:T}) where T
      println(T)
end

function testy(fun::Fun{Tuple{T},Vector{CV} where CV<:T}) where T
      :A
end


func = TypedFun{Tuple{Int64},Array{CV,1} where CV<:Int64}(x->[x])

supertype(typeof(func))
Fun{Tuple{Int64},Array{CV,1} where CV<:Int64}

#this works
testy(func)
> :A

#this doesn't work
test(func)

ERROR: UndefVarError: T not defined

why? and how can I fix it?

Thanks

2

can you provide a constructor for Fun ?

3

yeah did it in the original post.

4

the problem i saw was that: Array{CV,1} where CV<:Int64} is not a type. from slack:

julia> T = Array{A,1} where A<:Int
Array{A,1} where A<:Int64
julia> T.var
A<:Int64
julia> T.var.ub
Int64
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5

It is a type it is UnionAll . And in the dispatch it should have bounded with Int.
But it didn’t

1 Like
6

Here is a MWE showing the problem I think. I’m not sure what cause it but perhaps someone can explain it to me:

struct F{X} end
f(x::F{Vector{Y} where Y <: X}) where X = println(X)
f(F{Vector{Y} where Y <: Int}()) # errors
1 Like
7

Is this error related to:

struct test{A,B}
    a::A
    b::B
end

f = function(x::test{A,B}) where {A,B}
    test(x.a, x.b)
end

Results in error: UndefVarError: B not defined

f1 = function(x::test{A,B};) where {A,B}
    test(x.a, x.b)
end

But this has no error

1 Like
8

Welcome to the Julia discourse forum! I am not sure the issue is related to this topic — next time, please open a new discussion.

This looks like a bug, you may want to open an issue.

In the meantime, consider the workaround

f = function(x::test{A,B}) where B where A
    test(x.a, x.b)
end

also note that if you are just trying to define a method for f, not a closure,

function f(x::test{A,B}) where {A,B}
    test(x.a, x.b)
end

of course works. Finally, it is common to capitalize type names, eg Test.

2 Likes