Heterogeneous multi dict

[jw3126]

I can do

Dict(1 => 1, 2=> "two")

but

using DataStructures
MultiDict(1 => 1, 2 => "two")

throws an error:

LoadError: MethodError: no method matching DataStructures.MultiDict{K,V}(::Pair{Int64,Int64}, ::Pair{Int64,String})
Closest candidates are:
  DataStructures.MultiDict{K,V}{K,V}(!Matched::Pair{K,V}...) at /home/jan/.julia/v0.6/DataStructures/src/multi_dict.jl:36
  DataStructures.MultiDict{K,V}(::Any) at /home/jan/.julia/v0.6/DataStructures/src/multi_dict.jl:20
  DataStructures.MultiDict{K,V}{T}(::Any) at sysimg.jl:66
while loading In[27], in expression starting on line 2

is this expected?

[kmsquire]

Certainly not desired. https://github.com/JuliaLang/DataStructures.jl/blob/52615e84024f2ac666469fb8f2af95a6194ad84c/src/multi_dict.jl is almost certainly missing a relevant constructor. Pull requests welcome!

[jw3126]

Yeah I tried to fix it, but so far I keep hitting JuliaLang/julia#19159.

[kmsquire]

@wildart I originally thought this issue was related to SortedMultiDicts, because I forgot that you had contributed a MultiDict implementation. Since there are no docs for MultiDict, it's hard to know what the expected behavior or solution is here. Would you be able to add some documentation under doc/source/?

[bjarthur]

same problem for SortedDict:

julia> SortedDict(1 => 1, 2 => "two")
ERROR: MethodError: no method matching DataStructures.SortedDict{K,D,Ord<:Base.Order.Ordering}(::Pair{Int64,Int64}, ::Pair{Int64,String})
Closest candidates are:
  DataStructures.SortedDict{K,D,Ord<:Base.Order.Ordering}{K,D}(::Pair{K,D}...) at /Users/arthurb/.julia/v0.5/DataStructures/src/sorted_dict.jl:35
  DataStructures.SortedDict{K,D,Ord<:Base.Order.Ordering}{K,D,Ord<:Base.Order.Ordering}(::Ord<:Base.Order.Ordering, ::Pair{K,D}...) at /Users/arthurb/.julia/v0.5/DataStructures/src/sorted_dict.jl:48
  DataStructures.SortedDict{K,D,Ord<:Base.Order.Ordering}(::Any) at /Users/arthurb/.julia/v0.5/DataStructures/src/sorted_dict.jl:57
  ...

[StephenVavasis]

Yes, it does appear that there is a constructor missing for SortedDict (and also SortedMultiDict). As a temporary workaround, you can try

      SortedDict(Dict(1 => 1, 2 => "two"))