Cannot Iterate on CleverDicts with Abstract Types

[pulsipher]

With the recent changes made to CleverDict, iterating on such with abstract keys and/or values leads to an assertion error due to the code shown below (after deletion occurs thus switching to the OrderedDict):

MathOptInterface.jl/src/Utilities/CleverDicts.jl

Line 291 in e512af8

return el::Pair{K, V}, State(i)

Here is a simple contrived example:

using MathOptInterface
const MOIUC = MathOptInterface.Utilities.CleverDicts

data = MOIUC.CleverDict{MOI.VariableIndex, Number}()
new_key1 = MOIUC.add_item(data, 42.42)
new_key2 = MOIUC.add_item(data, 42.42)
delete!(data, new_key2)

for (k, v) in data
   println(v)
end

ERROR: TypeError: in typeassert, expected Pair{MathOptInterface.VariableIndex,Number}, got Pair{MathOptInterface.VariableIndex,Float64}
Stacktrace:
 [1] iterate(::MathOptInterface.Utilities.CleverDicts.CleverDict{MathOptInterface.VariableIndex,Number,typeof(MathOptInterface.Utilities.CleverDicts.key_to_index),getfield(MathOptInterface.Utilities.CleverDicts, Symbol("##1#2")){MathOptInterface.VariableIndex}}) at my_path\.julia\packages\MathOptInterface\R1y80\src\Utilities\CleverDicts.jl:291
 [2] top-level scope at .\REPL[37]:1

[odow]

This should probably be

return convert(Pair{K, V}, el), State(i)

What is the use-case?

[pulsipher]

I use these CleverDicts in InfiniteOpt.jl as a convenient container for storing my parameter, variable, and constraint objects. Some of these objects have parametric types (e.g., different parameter sets) which necessitate the use of an abstract type for the container values since I do not know what sets the user will select. Then I iterate over these containers at a few places in my code (e.g., model transcription). Here is a reference to the main InfiniteModel struct:
https://github.com/pulsipher/InfiniteOpt.jl/blob/8a25598d62a22cbf2c3d64729b89f0cb4d7d04fa/src/datatypes.jl#L839-L928

For now, I'll just restrict my MOI dependency to v0.9.14.

[odow]

Another option that probably doesn't hurt performance is to type the value as Any.

# TODO: replace Any with <:VariableData{<:InfiniteVariable}} once
# https://github.com/jump-dev/MathOptInterface.jl/issues/1157 is fixed.
infinite_vars::MOIUC.CleverDict{InfiniteVariableIndex, Any}

Actually, this probably won't work either.

[pulsipher]

Ya, that probably won't hurt the performance much, but you're right it sadly doesn't work (it was the first thing I tried). It only works with concrete types which are not readily possible in this application without introducing ambiguous type structures.