问题
The following code in Julia:
function foo(a::Vector{AbstractString})
end
foo(["a"])
gives the following error:
ERROR: MethodError: no method matching foo(::Array{String,1})
Closest candidates are:
foo(::Array{AbstractString,1}) at REPL[77]:2
Even though the following code runs, as expected:
function foo(a::Vector{String})
end
foo(["a"])
And further, AbstractString
generally matches String
as in:
function foo(::AbstractString)
end
foo("a")
How can I call a function with a Vector{AbstractString}
parameter if I have String
elements?
回答1:
You need to write the function signature like this:
function foo{S<:AbstractString}(a::Vector{S})
# do stuff
end
On Julia 0.6 and newer, it's also possible to write instead
function foo(a::Vector{<:AbstractString})
# do stuff
end
This is a consequence of parametric type invariance in Julia. See the chapter on types in the manual for more details.
来源:https://stackoverflow.com/questions/21465838/vectorabstractstring-function-parameter-wont-accept-vectorstring-input-in-j