向字符串对数组中添加项时的MethodError

Question

在对字符串对数组进行非常基本的操作时获得MethodError

julia> arr = Array{Pair{string, string}}(undef, 1)
1-element Array{Pair{string,string},1}:
#undef
julia> p = "str1" => "str2"
"str1" => "str2"
julia> push!(arr,p)
ERROR: MethodError: First argument to `convert` must be a Type, got string
Stacktrace:
[1] convert(::Type{Pair{string,string}}, ::Pair{String,String}) at ./pair.jl:71
[2] push!(::Array{Pair{string,string},1}, ::Pair{String,String}) at ./array.jl:934
[3] top-level scope at REPL[103]:1
julia> arr[1] = p
ERROR: MethodError: First argument to `convert` must be a Type, got string
Stacktrace:
[1] convert(::Type{Pair{string,string}}, ::Pair{String,String}) at ./pair.jl:71
[2] setindex!(::Array{Pair{string,string},1}, ::Pair{String,String}, ::Int64) at ./array.jl:847
[3] top-level scope at REPL[104]:1

Int对数组似乎没有这个问题。

julia> arr2 = Array{Pair{Int, Int}}(undef, 1)
1-element Array{Pair{Int64,Int64},1}:
0 => 0
julia> p2 = 1 => 2
1 => 2
julia> push!(arr2,p2)
2-element Array{Pair{Int64,Int64},1}:
0 => 0
1 => 2
julia> arr2[1] = p2
1 => 2

我错过了什么吗?

Answer 1

应该是:

arr = Array{Pair{String, String}}(undef, 1)

参数类型的正确性似乎是在构造函数中使用后才被检查的，因此这种不正确的数据结构是允许的。