Use dispatch in add single variable constraint

[joaquimg]

No description provided.

[guilhermebodin]

Can we close this? SingleVariable does not exist anymore in the current MOI versions.

[odow]

Closing. This is okay:

Xpress.jl/src/MOI/MOI_wrapper.jl

Lines 1411 to 1452 in b5bc1e7

	function MOI.add_constraint(
	model::Optimizer, f::MOI.VariableIndex, s::S
	) where {S <: SCALAR_SETS}
	info = _info(model, f)
	if info.type == BINARY
	lower, upper = _bounds(s)
	if lower !== nothing
	if lower > 1
	error("The problem is infeasible")
	end
	end
	if upper !== nothing
	if upper < 0
	error("The problem is infeasible")
	end
	end
	if lower !== nothing && upper !== nothing
	if (lower > 0 && upper < 1)
	error("The problem is infeasible")
	end
	end
	end
	if S <: MOI.LessThan{Float64}
	_throw_if_existing_upper(info.bound, info.type, S, f)
	info.bound = info.bound == GREATER_THAN ? LESS_AND_GREATER_THAN : LESS_THAN
	elseif S <: MOI.GreaterThan{Float64}
	_throw_if_existing_lower(info.bound, info.type, S, f)
	info.bound = info.bound == LESS_THAN ? LESS_AND_GREATER_THAN : GREATER_THAN
	elseif S <: MOI.EqualTo{Float64}
	_throw_if_existing_lower(info.bound, info.type, S, f)
	_throw_if_existing_upper(info.bound, info.type, S, f)
	info.bound = EQUAL_TO
	else
	@assert S <: MOI.Interval{Float64}
	_throw_if_existing_lower(info.bound, info.type, S, f)
	_throw_if_existing_upper(info.bound, info.type, S, f)
	info.bound = INTERVAL
	end
	index = MOI.ConstraintIndex{MOI.VariableIndex, typeof(s)}(f.value)
	MOI.set(model, MOI.ConstraintSet(), index, s)
	return index
	end

[joaquimg]

For future note.
We are not closing because single variable does not exist.
The issue is the same but for variable index.
We are closing because it does not seem to be a bottleneck. Although it seems to be against the julia manual performance tips.