[julia-users] How can I "call out" (from within a func in a module) to a later defined function?

[Robert Feldt]

Hi,

I want to be able to call out from a function (defined within a module) to 
a method with a specific name but that is defined outside the module. Let 
me try to show the actual code to help clarify:

module M

abstract G
s_type(g::G) = g.s_type

function new_s(g::G)
s = s_type(g)
s(g)
end

# This is the function that should call out to methods named start
# that are defined outside this module:
function g(g::G)
s = new_s(g)
println("start(", typeof(g), ", ", typeof(s), ")")
start(g, s)
end

abstract S

type DefaultS <: S
g
DefaultS(g::G) = new(g)
end

end

type G2 <: M.G
s_type

function G2()
new(M.DefaultS)
end
end

# This is the function I want to call out to from within the module M:
function start(g::G2, s::M.DefaultS)
1
end

g2 = G2()
s = M.DefaultS(g2)

Now if I call start directly it does as expected:

julia> start(g2, s)
1

But if I call through the g function in the module it complains:
ulia> M.g(g2)
start(G2, DefaultS)
ERROR: no method start(G2, DefaultS)
 in g at none:15

despite:

julia> methods(start)
# 1 method for generic function "start":
start(g::G2,s::DefaultS) at none:2

What have I missed? Thanks for any help,

Robert Feldt