There's a few things going on here. First, you only define one method for
`g` — your second definition overwrites the first because keyword arguments
don't participate in multiple dispatch. There's been a warning added here
in 0.5.
So the one method you define just takes one argument and one keyword
argument. That's why `g("bla", ["foo", "bar"])` isn't working. If you
instead call `g("bla", v=["foo", "bar"])`, you'll get a stack overflow
error with the second definition, and a type assertion failure with the
first. Instead of converting your `v` argument to a
`Vector{AbstractArray}`, you can just use the first definition with a type
parameter.
Finally, the `S not defined` error is a known surprising
behavior: https://github.com/JuliaLang/julia/issues/15613. When there's no
keyword argument given, how can Julia know what `S` should be?
On Friday, March 25, 2016 at 7:15:09 PM UTC-4, Dominique Orban wrote:
>
> I (think I) understand the issue in this thread:
> https://groups.google.com/forum/#!searchin/julia-users/AbstractString/julia-users/HBMDbnRTH9g/cuqa6hB8AQAJ
> but I have the same problem with a keyword argument:
>
> function g(s :: AbstractString; v :: Vector{AbstractString}=AbstractString
> [])
> println(s)
> for e in v
> println(v)
> end
> end
>
>
> I need to dispatch on the optional argument `v`, so:
>
> g{S <: AbstractString}(s :: AbstractString; v :: Vector{S}=Vector{S}[]) =
> g(s, v=convert(Vector{AbstractString}, v))
>
>
>
> but unfortunately:
>
> julia> g("bla", ["foo", "bar"])
> ERROR: MethodError: `g` has no method matching g(::ASCIIString, ::Array{
> ASCIIString,1})
> Closest candidates are:
> g(::AbstractString)
>
>
> Moreover,
>
> julia> g("boo")
> ERROR: UndefVarError: S not defined
>
>
> Any ideas?
>
