If first argument can be same concrete string type as element type of
keyword vector, then
Define function as:
function h{T<:AbstractString}(s::T; v::Vector{T}=T[])
println(s)
for e in v
println(e)
end
end
and call as:
julia> h("boo")
boo
julia> h("bla", v=["foo", "bar"])
bla
foo
bar
On Saturday, March 26, 2016 at 1:10:31 PM UTC+11, Dominique Orban wrote:
> That's what I ended up doing but keyword arguments have the advantage of
> being self-documenting. Thanks for the explanations.
>
> On Friday, March 25, 2016 at 10:07:54 PM UTC-4, Greg Plowman wrote:
>>
>> Thanks Matt, that helps my understanding of keyword arguments.
>>
>> It also occurs to me that if you don't really require *keyword*
>> arguments then you could define as:
>>
>> function g(s::AbstractString)
>> println(s)
>> end
>>
>> function g{S<:AbstractString}(s::AbstractString, v::Vector{S})
>> println(s)
>> for e in v
>> println(e)
>> end
>> end
>>
>> and call as:
>>
>> julia> g("boo")
>> boo
>>
>> julia> g("bla", ["foo", "bar"])
>> bla
>> foo
>> bar
>>
>>
>>
>> On Saturday, March 26, 2016 at 10:43:17 AM UTC+11, Matt Bauman wrote:
>>
>>> 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?
>>>>
>>>
