diff --git a/src/MOI/MOI_wrapper.jl b/src/MOI/MOI_wrapper.jl
index 997d7c19..bf2c1628 100644
--- a/src/MOI/MOI_wrapper.jl
+++ b/src/MOI/MOI_wrapper.jl
@@ -5,7 +5,7 @@
 
 const CleverDicts = MOI.Utilities.CleverDicts
 
-@enum(VariableType, CONTINUOUS, BINARY, INTEGER, SEMIINTEGER, SEMICONTINUOUS,)
+@enum(VariableType, CONTINUOUS, BINARY, INTEGER, SEMIINTEGER, SEMICONTINUOUS)
 
 @enum(ConstraintType, AFFINE, INDICATOR, QUADRATIC, SOC, RSOC, SOS_SET)
 
@@ -19,9 +19,9 @@ const CleverDicts = MOI.Utilities.CleverDicts
     EQUAL_TO,
 )
 
-@enum(ObjectiveType, SINGLE_VARIABLE, SCALAR_AFFINE, SCALAR_QUADRATIC,)
+@enum(ObjectiveType, SINGLE_VARIABLE, SCALAR_AFFINE, SCALAR_QUADRATIC)
 
-@enum(CallbackState, CB_NONE, CB_GENERIC, CB_LAZY, CB_USER_CUT, CB_HEURISTIC,)
+@enum(CallbackState, CB_NONE, CB_GENERIC, CB_LAZY, CB_USER_CUT, CB_HEURISTIC)
 
 const SCALAR_SETS = Union{
     MOI.GreaterThan{Float64},
@@ -95,6 +95,7 @@ mutable struct ConstraintInfo
     # perhaps call lazy on calls for writing lps and so on
     name::String
     type::ConstraintType
+
     function ConstraintInfo(
         row::Int,
         set::MOI.AbstractSet,
@@ -145,6 +146,11 @@ mutable struct IISData
     colbndtype::Vector{UInt8} # sense of the column bounds that participate
 end
 
+"""
+    Optimizer()
+
+Create a new Optimizer object.
+"""
 mutable struct Optimizer <: MOI.AbstractOptimizer
     # The low-level Xpress model.
     inner::XpressProblem
@@ -243,42 +249,30 @@ mutable struct Optimizer <: MOI.AbstractOptimizer
     message_callback::Union{Nothing,Tuple{Ptr{Nothing},_CallbackUserData}}
 
     params::Dict{Any,Any}
-    """
-        Optimizer()
 
-    Create a new Optimizer object.
-    """
     function Optimizer(; kwargs...)
         model = new()
-
         model.params = Dict{Any,Any}()
         model.log_level = 1 # is xpress default
         model.show_warning = true
         model.moi_warnings = true
         model.ignore_start = false
         model.post_solve = true
-
         model.solve_method = ""
         model.solve_relaxation = false
-
         model.message_callback = nothing
-
         model.termination_status = MOI.OPTIMIZE_NOT_CALLED
         model.primal_status = MOI.NO_SOLUTION
         model.dual_status = MOI.NO_SOLUTION
-
         for (name, value) in kwargs
             name = MOI.RawOptimizerAttribute(string(name))
             model.params[name] = value
         end
-
         model.variable_info =
             CleverDicts.CleverDict{MOI.VariableIndex,VariableInfo}()
         model.affine_constraint_info = Dict{Int,ConstraintInfo}()
         model.sos_constraint_info = Dict{Int,ConstraintInfo}()
-
         MOI.empty!(model)  # inner is initialized here
-
         return model
     end
 end
@@ -287,24 +281,21 @@ Base.show(io::IO, model::Optimizer) = show(io, model.inner)
 
 function MOI.empty!(model::Optimizer)
     model.inner = XpressProblem()
-
     for (name, value) in model.params
         MOI.set(model, name, value)
     end
-
     MOI.set(model, MOI.RawOptimizerAttribute("MPSNAMELENGTH"), 64)
     MOI.set(model, MOI.RawOptimizerAttribute("CALLBACKFROMMASTERTHREAD"), 1)
-
     MOI.set(
         model,
         MOI.RawOptimizerAttribute("XPRESS_WARNING_WINDOWS"),
         model.show_warning,
     )
-
-    # disable log caching previous state
     log_level = model.log_level
-    log_level != 0 && MOI.set(model, MOI.RawOptimizerAttribute("OUTPUTLOG"), 0)
     # silently load a empty model - to avoid useless printing
+    if log_level != 0
+        MOI.set(model, MOI.RawOptimizerAttribute("OUTPUTLOG"), 0)
+    end
     @checked Lib.XPRSloadlp(
         model.inner,
         "",
@@ -321,10 +312,9 @@ function MOI.empty!(model::Optimizer)
         C_NULL,
         C_NULL,
     )
-    # re-enable logging
-    log_level != 0 &&
+    if log_level != 0
         MOI.set(model, MOI.RawOptimizerAttribute("OUTPUTLOG"), log_level)
-
+    end
     model.name = ""
     model.objective_type = SCALAR_AFFINE
     model.is_objective_set = false
@@ -335,31 +325,23 @@ function MOI.empty!(model::Optimizer)
     empty!(model.sos_constraint_info)
     model.name_to_variable = nothing
     model.name_to_constraint_index = nothing
-
     model.cached_solution = nothing
     model.basis_status = nothing
     model.conflict = nothing
-
     model.termination_status = MOI.OPTIMIZE_NOT_CALLED
     model.primal_status = MOI.NO_SOLUTION
     model.dual_status = MOI.NO_SOLUTION
-
     model.callback_cached_solution = nothing
     model.cb_cut_data = CallbackCutData(false, Array{Lib.XPRScut}(undef, 0))
     model.callback_state = CB_NONE
     model.cb_exception = nothing
-
     model.forward_sensitivity_cache = nothing
     model.backward_sensitivity_cache = nothing
-
     model.lazy_callback = nothing
     model.user_cut_callback = nothing
     model.heuristic_callback = nothing
-
     model.has_generic_callback = false
     model.callback_data = nothing
-    # model.message_callback = nothing
-
     for (name, value) in model.params
         MOI.set(model, name, value)
     end
@@ -367,40 +349,29 @@ function MOI.empty!(model::Optimizer)
 end
 
 function MOI.is_empty(model::Optimizer)
-    !isempty(model.name) && return false
-    model.objective_type != SCALAR_AFFINE && return false
-    model.is_objective_set == true && return false
-    model.objective_sense !== nothing && return false
-    !isempty(model.variable_info) && return false
-    length(model.affine_constraint_info) != 0 && return false
-    length(model.sos_constraint_info) != 0 && return false
-    model.name_to_variable !== nothing && return false
-    model.name_to_constraint_index !== nothing && return false
-
-    model.cached_solution !== nothing && return false
-    model.basis_status !== nothing && return false
-    model.conflict !== nothing && return false
-
-    model.termination_status != MOI.OPTIMIZE_NOT_CALLED && return false
-    model.primal_status != MOI.NO_SOLUTION && return false
-    model.dual_status != MOI.NO_SOLUTION && return false
-
-    model.callback_cached_solution !== nothing && return false
-    # model.cb_cut_data !== nothing && return false
-    model.callback_state != CB_NONE && return false
-    model.cb_exception !== nothing && return false
-
-    model.lazy_callback !== nothing && return false
-    model.user_cut_callback !== nothing && return false
-    model.heuristic_callback !== nothing && return false
-
-    model.has_generic_callback && return false
-    model.callback_data !== nothing && return false
-
-    # model.message_callback !== nothing && return false
-    # otherwise jump complains it is not empty
-
-    return true
+    return isempty(model.name) &&
+           model.objective_type == SCALAR_AFFINE &&
+           !model.is_objective_set &&
+           model.objective_sense === nothing &&
+           isempty(model.variable_info) &&
+           isempty(model.affine_constraint_info) &&
+           isempty(model.sos_constraint_info) &&
+           model.name_to_variable === nothing &&
+           model.name_to_constraint_index === nothing &&
+           model.cached_solution === nothing &&
+           model.basis_status === nothing &&
+           model.conflict === nothing &&
+           model.termination_status == MOI.OPTIMIZE_NOT_CALLED &&
+           model.primal_status == MOI.NO_SOLUTION &&
+           model.dual_status == MOI.NO_SOLUTION &&
+           model.callback_cached_solution === nothing &&
+           model.callback_state == CB_NONE &&
+           model.cb_exception === nothing &&
+           model.lazy_callback === nothing &&
+           model.user_cut_callback === nothing &&
+           model.heuristic_callback === nothing &&
+           !model.has_generic_callback &&
+           model.callback_data === nothing
 end
 
 function reset_cached_solution(model::Optimizer)
@@ -467,55 +438,6 @@ function MOI.get(optimizer::Optimizer, ::MOI.SolverVersion)
     return MOI.get(optimizer, MOI.RawOptimizerAttribute("XPRESSVERSION"))
 end
 
-function MOI.supports(
-    ::Optimizer,
-    ::MOI.ObjectiveFunction{F},
-) where {
-    F<:Union{
-        MOI.VariableIndex,
-        MOI.ScalarAffineFunction{Float64},
-        MOI.ScalarQuadraticFunction{Float64},
-    },
-}
-    return true
-end
-
-function MOI.supports_constraint(
-    ::Optimizer,
-    ::Type{MOI.VariableIndex},
-    ::Type{F},
-) where {
-    F<:Union{
-        MOI.EqualTo{Float64},
-        MOI.LessThan{Float64},
-        MOI.GreaterThan{Float64},
-        MOI.Interval{Float64},
-        MOI.ZeroOne,
-        MOI.Integer,
-        MOI.Semicontinuous{Float64},
-        MOI.Semiinteger{Float64},
-    },
-}
-    return true
-end
-
-function MOI.supports_constraint(
-    ::Optimizer,
-    ::Type{MOI.VectorOfVariables},
-    ::Type{F},
-) where {
-    F<:Union{
-        MOI.SOS1{Float64},
-        MOI.SOS2{Float64},
-        MOI.SecondOrderCone,
-        MOI.RotatedSecondOrderCone,
-    },
-}
-    # Xpress only supports disjoint sets of SOC and RSOC (with no affine forms)
-    # hence we only allow constraints on creation
-    return true
-end
-
 function MOI.supports_add_constrained_variables(
     ::Optimizer,
     ::Type{F},
@@ -554,20 +476,10 @@ function MOI.supports_constraint(
     return true
 end
 
-MOI.supports(::Optimizer, ::MOI.VariableName, ::Type{MOI.VariableIndex}) = true
-function MOI.supports(
-    ::Optimizer,
-    ::MOI.ConstraintName,
-    ::Type{<:MOI.ConstraintIndex},
-)
-    return true
-end
+#=
+    MOI.RawOptimizerAttribute
+=#
 
-MOI.supports(::Optimizer, ::MOI.Name) = true
-MOI.supports(::Optimizer, ::MOI.Silent) = true
-MOI.supports(::Optimizer, ::MOI.NumberOfThreads) = true
-MOI.supports(::Optimizer, ::MOI.TimeLimitSec) = true
-MOI.supports(::Optimizer, ::MOI.ObjectiveSense) = true
 MOI.supports(::Optimizer, ::MOI.RawOptimizerAttribute) = true
 
 function MOI.set(model::Optimizer, param::MOI.RawOptimizerAttribute, value)
@@ -598,10 +510,10 @@ function MOI.set(model::Optimizer, param::MOI.RawOptimizerAttribute, value)
         reset_message_callback(model)
     elseif param == MOI.RawOptimizerAttribute("OUTPUTLOG")
         model.log_level = value
-        Xpress.setcontrol!(model.inner, "OUTPUTLOG", value)
+        setcontrol!(model.inner, "OUTPUTLOG", value)
         reset_message_callback(model)
     else
-        Xpress.setcontrol!(model.inner, param.name, value)
+        setcontrol!(model.inner, param.name, value)
     end
     return
 end
@@ -612,10 +524,10 @@ function reset_message_callback(model)
         @checked Lib.XPRSremovecbmessage(model.inner, C_NULL, C_NULL)
         model.message_callback = nothing
     end
-    if model.inner.logfile == "" &&    # no file -> screen
-       model.log_level != 0        # has log
+    if isempty(model.inner.logfile) && model.log_level != 0
         model.message_callback = setoutputcb!(model.inner, model.show_warning)
     end
+    return
 end
 
 function MOI.get(model::Optimizer, param::MOI.RawOptimizerAttribute)
@@ -631,11 +543,16 @@ function MOI.get(model::Optimizer, param::MOI.RawOptimizerAttribute)
         return model.solve_method
     elseif param == MOI.RawOptimizerAttribute("XPRESS_WARNING_WINDOWS")
         return model.show_warning
-    else
-        return Xpress.get_control_or_attribute(model.inner, param.name)
     end
+    return get_control_or_attribute(model.inner, param.name)
 end
 
+#=
+    MOI.TimeLimitSec
+=#
+
+MOI.supports(::Optimizer, ::MOI.TimeLimitSec) = true
+
 function MOI.set(model::Optimizer, ::MOI.TimeLimitSec, limit::Real)
     # positive values would mean that its stops after `limit` seconds
     # iff there is already a MIP solution available.
@@ -659,49 +576,50 @@ end
 
 function MOI.get(model::Optimizer, ::MOI.ListOfVariableAttributesSet)
     ret = MOI.AbstractVariableAttribute[]
-    found_name =
-        any(!isempty(info.name) for info in values(model.variable_info))
-    found_start =
-        any(info.start !== nothing for info in values(model.variable_info))
-    if found_name
+    if any(!isempty(info.name) for info in values(model.variable_info))
         push!(ret, MOI.VariableName())
     end
-    if found_start
+    if any(info.start !== nothing for info in values(model.variable_info))
         push!(ret, MOI.VariablePrimalStart())
     end
     return ret
 end
 
 function MOI.get(model::Optimizer, ::MOI.ListOfModelAttributesSet)
+    attributes = MOI.AbstractModelAttribute[]
     if MOI.is_empty(model)
-        return Any[]
+        return attributes
     end
-    attributes = Any[]
     if model.objective_sense !== nothing
         push!(attributes, MOI.ObjectiveSense())
     end
-    typ = MOI.get(model, MOI.ObjectiveFunctionType())
-    if typ !== nothing
-        push!(attributes, MOI.ObjectiveFunction{typ}())
+    F = MOI.get(model, MOI.ObjectiveFunctionType())
+    if F !== nothing
+        push!(attributes, MOI.ObjectiveFunction{F}())
     end
-    if MOI.get(model, MOI.Name()) != ""
+    if !isempty(MOI.get(model, MOI.Name()))
         push!(attributes, MOI.Name())
     end
     return attributes
 end
 
+function MOI.get(
+    ::Optimizer,
+    ::MOI.ListOfConstraintAttributesSet{MOI.VariableIndex},
+)
+    return MOI.AbstractConstraintAttribute[]
+end
+
 function MOI.get(
     model::Optimizer,
     ::MOI.ListOfConstraintAttributesSet{F,S},
-) where {S,F}
+) where {F,S}
     ret = MOI.AbstractConstraintAttribute[]
-    constraint_indices = MOI.get(model, MOI.ListOfConstraintIndices{F,S}())
-    found_name = any(
-        !isempty(MOI.get(model, MOI.ConstraintName(), index)) for
-        index in constraint_indices
-    )
-    if found_name
-        push!(ret, MOI.ConstraintName())
+    for ci in MOI.get(model, MOI.ListOfConstraintIndices{F,S}())
+        if !isempty(MOI.get(model, MOI.ConstraintName(), ci))
+            push!(ret, MOI.ConstraintName())
+            break
+        end
     end
     return ret
 end
@@ -762,7 +680,6 @@ function _indices_and_coefficients(
         I[i] = _info(model, term.variable_1).column
         J[i] = _info(model, term.variable_2).column
         V[i] = term.coefficient
-
         # MOI    represents objective as 0.5 x' Q x
         # Example: obj = 2x^2 + x*y + y^2
         #              = 2x^2 + (1/2)*x*y + (1/2)*y*x + y^2
@@ -784,7 +701,6 @@ function _indices_and_coefficients(
         #     Hence,
         #     Only for constraints, MOI -> Xpress => divide all by 2
         #     Only for constraints, Xpress -> MOI => multiply all by 2
-
     end
     for (i, term) in enumerate(f.affine_terms)
         indices[i] = _info(model, term.variable).column
@@ -837,14 +753,14 @@ function MOI.add_variable(model::Optimizer)
     info.column = length(model.variable_info)
     @checked Lib.XPRSaddcols(
         model.inner,
-        1,#length(_dbdl)::Int,
-        0,#length(_dmatval)::Int,
-        Ref(0.0),#_dobj::Vector{Float64},
-        C_NULL,#Cint.(_mrwind::Vector{Int}),
-        C_NULL,#Cint.(_mrstart::Vector{Int}),
-        C_NULL,#_dmatval::Vector{Float64},
-        Ref(-Inf),#_dbdl::Vector{Float64},
-        Ref(Inf),#_dbdu::Vector{Float64}
+        1,          # length(_dbdl)::Int,
+        0,          # length(_dmatval)::Int,
+        Ref(0.0),   # _dobj::Vector{Float64},
+        C_NULL,     # Cint.(_mrwind::Vector{Int}),
+        C_NULL,     # Cint.(_mrstart::Vector{Int}),
+        C_NULL,     # _dmatval::Vector{Float64},
+        Ref(-Inf),  # _dbdl::Vector{Float64},
+        Ref(Inf),   # _dbdu::Vector{Float64}
     )
     return index
 end
@@ -852,14 +768,14 @@ end
 function MOI.add_variables(model::Optimizer, N::Int)
     @checked Lib.XPRSaddcols(
         model.inner,
-        N,#length(_dbdl)::Int,
-        0,#length(_dmatval)::Int,
-        zeros(N),# _dobj::Vector{Float64},
-        C_NULL,#Cint.(_mrwind::Vector{Int}),
-        C_NULL,#Cint.(_mrstart::Vector{Int}),
-        C_NULL,# _dmatval::Vector{Float64},
-        fill(-Inf, N),# _dbdl::Vector{Float64},
-        fill(Inf, N),# _dbdu::Vector{Float64}
+        N,              # length(_dbdl)::Int,
+        0,              # length(_dmatval)::Int,
+        zeros(N),       # _dobj::Vector{Float64},
+        C_NULL,         # Cint.(_mrwind::Vector{Int}),
+        C_NULL,         # Cint.(_mrstart::Vector{Int}),
+        C_NULL,         # _dmatval::Vector{Float64},
+        fill(-Inf, N),  #  _dbdl::Vector{Float64},
+        fill(Inf, N),   # _dbdu::Vector{Float64}
     )
     indices = Vector{MOI.VariableIndex}(undef, N)
     num_variables = length(model.variable_info)
@@ -918,7 +834,7 @@ end
 function _rebuild_name_to_variable(model::Optimizer)
     model.name_to_variable = Dict{String,Union{Nothing,MOI.VariableIndex}}()
     for (index, info) in model.variable_info
-        if info.name == ""
+        if isempty(info.name)
             continue
         end
         if haskey(model.name_to_variable, info.name)
@@ -930,6 +846,12 @@ function _rebuild_name_to_variable(model::Optimizer)
     return
 end
 
+#=
+    MOI.VariableName
+=#
+
+MOI.supports(::Optimizer, ::MOI.VariableName, ::Type{MOI.VariableIndex}) = true
+
 function MOI.get(model::Optimizer, ::MOI.VariableName, v::MOI.VariableIndex)
     return _info(model, v).name
 end
@@ -943,8 +865,7 @@ function MOI.set(
     info = _info(model, v)
     info.name = name
     # Note: don't set the string names in the Xpress C API because it complains
-    # on duplicate variables.
-    # That is, don't call `Lib.XPRSaddnames`.
+    # on duplicate variables, that is, don't call `Lib.XPRSaddnames`.
     model.name_to_variable = nothing
     return
 end
@@ -970,17 +891,13 @@ function forward(model::Optimizer)
     spare_rows =
         @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_SPAREROWS, _)::Int
     cols = @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_COLS, _)::Int
-
-    #1 - Create vector 'aux_vector' of size ROWS of type Float64 (constraints)
+    # 1 - Create vector 'aux_vector' of size ROWS of type Float64 (constraints)
     aux_vector = copy(model.forward_sensitivity_cache.input)
-
-    #2 - Call XPRSftran with vector 'aux_vector' as an argument
+    # 2 - Call XPRSftran with vector 'aux_vector' as an argument
     @checked Lib.XPRSftran(model.inner, aux_vector)
-
-    #3 - Create Dict of Basic variable to All variables
+    # 3 - Create Dict of Basic variable to All variables
     basic_variables_ordered = Vector{Cint}(undef, rows)
     @checked Lib.XPRSgetpivotorder(model.inner, basic_variables_ordered)
-
     aux_dict = Dict{Int,Int}()
     for i in 1:length(basic_variables_ordered)
         if rows + spare_rows <=
@@ -989,13 +906,12 @@ function forward(model::Optimizer)
             aux_dict[i] = basic_variables_ordered[i] - (rows + spare_rows) + 1
         end
     end
-
-    #5 - Populate vector of All variables with the correct value of the Basic variables
+    # 5 - Populate vector of All variables with the correct value of the Basic
+    #     variables
     fill!(model.forward_sensitivity_cache.output, 0.0)
     for (bi, vi) in aux_dict
         model.forward_sensitivity_cache.output[vi] = aux_vector[bi]
     end
-
     return
 end
 
@@ -1004,11 +920,9 @@ function backward(model::Optimizer)
     spare_rows =
         @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_SPAREROWS, _)::Int
     cols = @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_COLS, _)::Int
-
-    #1 - Get Basic variables
+    # 1 - Get Basic variables
     basic_variables_ordered = Vector{Int32}(undef, rows)
     @checked Lib.XPRSgetpivotorder(model.inner, basic_variables_ordered)
-
     aux_dict = Dict{Int,Int}()
     for i in 1:length(basic_variables_ordered)
         if rows + spare_rows <=
@@ -1017,19 +931,17 @@ function backward(model::Optimizer)
             aux_dict[i] = basic_variables_ordered[i] - (rows + spare_rows) + 1
         end
     end
-
-    #2 - Create vector 'aux_vector' of size ROWS of type Float64 (constraints) initialized at zero
+    # 2 - Create vector 'aux_vector' of size ROWS of type Float64 (constraints)
+    #     initialized at zero
     aux_vector = zeros(rows)
-
-    #3 - Populate vector 'aux_vector' with the respective values in the correct positions of the basic variables
+    # 3 - Populate vector 'aux_vector' with the respective values in the correct
+    #     positions of the basic variables
     for (bi, vi) in aux_dict
         aux_vector[bi] = model.backward_sensitivity_cache.input[vi]
     end
-
-    #4 - Call XPRSbtran with vector 'aux_vector' as an argument
+    # 4 - Call XPRSbtran with vector 'aux_vector' as an argument
     @checked Lib.XPRSbtran(model.inner, aux_vector)
-
-    #5 - Set constraint_output equal to vector 'aux_vector'
+    # 5 - Set constraint_output equal to vector 'aux_vector'
     model.backward_sensitivity_cache.output .= aux_vector
     return
 end
@@ -1119,60 +1031,64 @@ end
 ###
 
 function _zero_objective(model::Optimizer)
-    num_vars = length(model.variable_info)
-    obj = zeros(Float64, num_vars)
     if model.objective_type == SCALAR_QUADRATIC
         # We need to zero out the existing quadratic objective.
         @checked Lib.XPRSdelqmatrix(model.inner, -1)
     end
+    num_vars = Cint(length(model.variable_info))
     @checked Lib.XPRSchgobj(
         model.inner,
-        Cint(num_vars),
+        num_vars,
         collect(Cint(0):Cint(num_vars - 1)),
-        obj,
+        zeros(Float64, num_vars),
     )
     @checked Lib.XPRSchgobj(model.inner, Cint(1), Ref{Cint}(-1), Ref(0.0))
     return
 end
 
+#=
+    MOI.ObjectiveSense
+=#
+
+MOI.supports(::Optimizer, ::MOI.ObjectiveSense) = true
+
 function MOI.set(
     model::Optimizer,
     ::MOI.ObjectiveSense,
     sense::MOI.OptimizationSense,
 )
-    # TODO: should this propagate across a `MOI.empty!(optimizer)` call
     if sense == MOI.MIN_SENSE
-        objsense = :Min
+        @checked Lib.XPRSchgobjsense(model.inner, Lib.XPRS_OBJ_MINIMIZE)
     elseif sense == MOI.MAX_SENSE
-        objsense = :Max
+        @checked Lib.XPRSchgobjsense(model.inner, Lib.XPRS_OBJ_MAXIMIZE)
     else
         @assert sense == MOI.FEASIBILITY_SENSE
         _zero_objective(model)
-        objsense = :Min
-    end
-    v =
-        objsense == :maximize ||
-        objsense == :Max ||
-        objsense == Lib.XPRS_OBJ_MAXIMIZE ? Lib.XPRS_OBJ_MAXIMIZE :
-        objsense == :minimize ||
-        objsense == :Min ||
-        objsense == Lib.XPRS_OBJ_MINIMIZE ? Lib.XPRS_OBJ_MINIMIZE :
-        throw(
-            ArgumentError(
-                "Invalid objective sense: $objsense. It can only be `:maximize`, `:minimize`, `:Max`, `:Min`, `$(Lib.XPRS_OBJ_MAXIMIZE)`, or `$(Lib.XPRS_OBJ_MINIMIZE)`.",
-            ),
-        )
-    @checked Lib.XPRSchgobjsense(model.inner, v)
+        @checked Lib.XPRSchgobjsense(model.inner, Lib.XPRS_OBJ_MINIMIZE)
+    end
     model.objective_sense = sense
     return
 end
 
 function MOI.get(model::Optimizer, ::MOI.ObjectiveSense)
-    if model.objective_sense !== nothing
-        return model.objective_sense
-    else
-        return MOI.FEASIBILITY_SENSE
-    end
+    return something(model.objective_sense, MOI.FEASIBILITY_SENSE)
+end
+
+#=
+    MOI.ObjectiveFunction
+=#
+
+function MOI.supports(
+    ::Optimizer,
+    ::MOI.ObjectiveFunction{F},
+) where {
+    F<:Union{
+        MOI.VariableIndex,
+        MOI.ScalarAffineFunction{Float64},
+        MOI.ScalarQuadraticFunction{Float64},
+    },
+}
+    return true
 end
 
 function MOI.set(
@@ -1352,6 +1268,25 @@ end
 ##  VariableIndex-in-Set constraints.
 ##
 
+function MOI.supports_constraint(
+    ::Optimizer,
+    ::Type{MOI.VariableIndex},
+    ::Type{S},
+) where {
+    S<:Union{
+        MOI.EqualTo{Float64},
+        MOI.LessThan{Float64},
+        MOI.GreaterThan{Float64},
+        MOI.Interval{Float64},
+        MOI.ZeroOne,
+        MOI.Integer,
+        MOI.Semicontinuous{Float64},
+        MOI.Semiinteger{Float64},
+    },
+}
+    return true
+end
+
 function _info(
     model::Optimizer,
     c::MOI.ConstraintIndex{MOI.VariableIndex,<:Any},
@@ -2205,57 +2140,6 @@ function MOI.get(
     return MOI.Semiinteger(lower, upper)
 end
 
-function MOI.get(
-    model::Optimizer,
-    ::MOI.ConstraintName,
-    c::MOI.ConstraintIndex{MOI.VariableIndex,S},
-) where {S}
-    MOI.throw_if_not_valid(model, c)
-    info = _info(model, c)
-    if S <: MOI.LessThan
-        return info.lessthan_name
-    elseif S <: Union{MOI.GreaterThan,MOI.Interval,MOI.EqualTo}
-        return info.greaterthan_interval_or_equalto_name
-    else
-        @assert S <: Union{
-            MOI.ZeroOne,
-            MOI.Integer,
-            MOI.Semiinteger,
-            MOI.Semicontinuous,
-        }
-        return info.type_constraint_name
-    end
-end
-
-function MOI.set(
-    model::Optimizer,
-    ::MOI.ConstraintName,
-    c::MOI.ConstraintIndex{MOI.VariableIndex,S},
-    name::String,
-) where {S}
-    MOI.throw_if_not_valid(model, c)
-    info = _info(model, c)
-    old_name = ""
-    if S <: MOI.LessThan
-        old_name = info.lessthan_name
-        info.lessthan_name = name
-    elseif S <: Union{MOI.GreaterThan,MOI.Interval,MOI.EqualTo}
-        old_name = info.greaterthan_interval_or_equalto_name
-        info.greaterthan_interval_or_equalto_name = name
-    else
-        @assert S <: Union{
-            MOI.ZeroOne,
-            MOI.Integer,
-            MOI.Semiinteger,
-            MOI.Semicontinuous,
-        }
-        info.type_constraint_name
-        info.type_constraint_name = name
-    end
-    model.name_to_constraint_index = nothing
-    return
-end
-
 ###
 ### ScalarAffineFunction-in-Set
 ###
@@ -2446,7 +2330,7 @@ end
 
 function _get_affine_terms(model::Optimizer, c::MOI.ConstraintIndex)
     row = _info(model, c).row
-    nzcnt_max = Xpress.n_non_zero_elements(model.inner)
+    nzcnt_max = n_non_zero_elements(model.inner)
 
     _nzcnt = Ref(Cint(0))
     @checked Lib.XPRSgetrows(
@@ -2503,6 +2387,25 @@ function MOI.get(
     return MOI.ScalarAffineFunction(terms, 0.0)
 end
 
+#=
+    MOI.ConstraintName
+=#
+
+function MOI.supports(
+    ::Optimizer,
+    ::MOI.ConstraintName,
+    ::Type{<:MOI.ConstraintIndex{F}},
+) where {
+    F<:Union{
+        MOI.VectorAffineFunction{Float64},
+        MOI.ScalarAffineFunction{Float64},
+        MOI.ScalarQuadraticFunction{Float64},
+        MOI.VectorOfVariables,
+    },
+}
+    return true
+end
+
 function MOI.get(
     model::Optimizer,
     ::MOI.ConstraintName,
@@ -2683,7 +2586,7 @@ function MOI.get(
     # row = info.row
     # set_cte = MOI.constant(info.set.set)
     # # a^T x + b <= c ===> a^T <= c - b
-    # Xpress.getrhs!(model.inner, rhs, row, row)
+    # getrhs!(model.inner, rhs, row, row)
     # return MOI.Indicator{A}(S(rhs[1]))
     return _info(model, c).set
 end
@@ -2735,7 +2638,7 @@ function MOI.add_constraint(
     @checked Lib.XPRSsetindicators(
         model.inner,
         1,
-        Ref{Cint}(Xpress.n_constraints(model.inner) - 1),
+        Ref{Cint}(n_constraints(model.inner) - 1),
         Ref{Cint}(con_value - 1),
         Ref{Cint}(indicator_activation(Val{A})),
     )
@@ -2819,7 +2722,7 @@ function MOI.add_constraint(
     J .-= 1
     @checked Lib.XPRSaddqmatrix(
         model.inner,
-        Xpress.n_constraints(model.inner) - 1,
+        n_constraints(model.inner) - 1,
         Cint(length(I)),
         I,
         J,
@@ -2880,6 +2783,23 @@ end
 ### VectorOfVariables-in-SOS{I|II}
 ###
 
+function MOI.supports_constraint(
+    ::Optimizer,
+    ::Type{MOI.VectorOfVariables},
+    ::Type{F},
+) where {
+    F<:Union{
+        MOI.SOS1{Float64},
+        MOI.SOS2{Float64},
+        MOI.SecondOrderCone,
+        MOI.RotatedSecondOrderCone,
+    },
+}
+    # Xpress only supports disjoint sets of SOC and RSOC (with no affine forms)
+    # hence we only allow constraints on creation
+    return true
+end
+
 const SOS = Union{MOI.SOS1{Float64},MOI.SOS2{Float64}}
 
 function _info(
@@ -3033,6 +2953,7 @@ function pre_solve_reset(model::Optimizer)
     reset_cached_solution(model)
     return
 end
+
 function check_cb_exception(model::Optimizer)
     if model.cb_exception !== nothing
         e = model.cb_exception
@@ -3042,9 +2963,7 @@ function check_cb_exception(model::Optimizer)
     return
 end
 
-function is_mip(model)
-    return Xpress.is_mixedinteger(model.inner) && !model.solve_relaxation
-end
+is_mip(model) = is_mixedinteger(model.inner) && !model.solve_relaxation
 
 function _set_MIP_start(model)
     colind, solval = Cint[], Cdouble[]
@@ -3065,7 +2984,7 @@ function MOI.optimize!(model::Optimizer)
     # Initialize callbacks if necessary.
     if check_moi_callback_validity(model)
         if model.moi_warnings &&
-           Xpress.getcontrol(model.inner, Lib.XPRS_HEURSTRATEGY) != 0
+           getcontrol(model.inner, Lib.XPRS_HEURSTRATEGY) != 0
             @warn "Callbacks in XPRESS might not work correctly with HEURSTRATEGY != 0"
         end
         MOI.set(model, CallbackFunction(), default_moi_callback(model))
@@ -3092,17 +3011,14 @@ function MOI.optimize!(model::Optimizer)
     end
     model.cached_solution.solve_time = time() - start_time
     check_cb_exception(model)
-
-    # should be almost a no-op if not needed
-    # might have minor overhead due to memory being freed
+    # Should be almost a no-op if not needed. Might have minor overhead due to
+    # memory being freed
     if model.post_solve
         @checked Lib.XPRSpostsolve(model.inner)
     end
-
     model.termination_status = _cache_termination_status(model)
     model.primal_status = _cache_primal_status(model)
     model.dual_status = _cache_dual_status(model)
-
     # TODO: add @checked here - must review statuses
     if is_mip(model)
         # TODO @checked (only works if not in [MOI.NO_SOLUTION, MOI.INFEASIBILITY_CERTIFICATE, MOI.INFEASIBLE_POINT])
@@ -3124,7 +3040,6 @@ function MOI.optimize!(model::Optimizer)
     end
     model.cached_solution.linear_primal .=
         rhs .- model.cached_solution.linear_primal
-
     status = MOI.get(model, MOI.PrimalStatus())
     if status == MOI.INFEASIBILITY_CERTIFICATE
         has_Ray = Int64[0]
@@ -3154,6 +3069,7 @@ function _throw_if_optimize_in_progress(model, attr)
     if model.callback_state != CB_NONE
         throw(MOI.OptimizeInProgress(attr))
     end
+    return
 end
 
 function MOI.get(model::Optimizer, attr::MOI.RawStatusString)
@@ -3167,14 +3083,14 @@ function MOI.get(model::Optimizer, attr::MOI.RawStatusString)
             Lib.XPRS_MIPSTATUS,
             _,
         )::Int
-        return Xpress.MIPSTATUS_STRING[stat] * " - " * stop_str
+        return MIPSTATUS_STRING[stat] * " - " * stop_str
     else
         stat = @_invoke Lib.XPRSgetintattrib(
             model.inner,
             Lib.XPRS_LPSTATUS,
             _,
         )::Int
-        return Xpress.LPSTATUS_STRING[stat] * " - " * stop_str
+        return LPSTATUS_STRING[stat] * " - " * stop_str
     end
 end
 
@@ -3397,6 +3313,10 @@ function MOI.get(model::Optimizer, attr::MOI.DualStatus)
     return model.dual_status
 end
 
+#=
+    MOI.VariablePrimal
+=#
+
 function MOI.get(
     model::Optimizer,
     attr::MOI.VariablePrimal,
@@ -3408,6 +3328,10 @@ function MOI.get(
     return model.cached_solution.variable_primal[column]
 end
 
+#=
+    MOI.ConstraintPrimal
+=#
+
 function MOI.get(
     model::Optimizer,
     attr::MOI.ConstraintPrimal,
@@ -3440,6 +3364,10 @@ function MOI.get(
     return model.cached_solution.linear_primal[row]
 end
 
+#=
+    MOI.ConstraintDual
+=#
+
 function _dual_multiplier(model::Optimizer)
     return MOI.get(model, MOI.ObjectiveSense()) == MOI.MIN_SENSE ? 1.0 : -1.0
 end
@@ -3490,10 +3418,6 @@ function _farkas_variable_dual(model::Optimizer, col::Int64)
     )
 end
 
-#=
-    Duals
-=#
-
 function MOI.get(
     model::Optimizer,
     attr::MOI.ConstraintDual,
@@ -3613,46 +3537,40 @@ function MOI.get(
     return _dual_multiplier(model) * pi
 end
 
+#=
+    MOI.ObjectiveValue
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.ObjectiveValue)
     _throw_if_optimize_in_progress(model, attr)
     MOI.check_result_index_bounds(model, attr)
-    if is_mip(model)
-        return @_invoke Lib.XPRSgetdblattrib(
-            model.inner,
-            Lib.XPRS_MIPOBJVAL,
-            _,
-        )::Float64
-    else
-        return @_invoke Lib.XPRSgetdblattrib(
-            model.inner,
-            Lib.XPRS_LPOBJVAL,
-            _,
-        )::Float64
-    end
+    attr = is_mip(model) ? Lib.XPRS_MIPOBJVAL : Lib.XPRS_LPOBJVAL
+    return @_invoke Lib.XPRSgetdblattrib(model.inner, attr, _)::Float64
 end
 
+#=
+    MOI.ObjectiveBound
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.ObjectiveBound)
     _throw_if_optimize_in_progress(model, attr)
-    if is_mip(model)
-        return @_invoke Lib.XPRSgetdblattrib(
-            model.inner,
-            Lib.XPRS_BESTBOUND,
-            _,
-        )::Float64
-    else
-        return @_invoke Lib.XPRSgetdblattrib(
-            model.inner,
-            Lib.XPRS_LPOBJVAL,
-            _,
-        )::Float64
-    end
+    attr = is_mip(model) ? Lib.XPRS_BESTBOUND : Lib.XPRS_LPOBJVAL
+    return @_invoke Lib.XPRSgetdblattrib(model.inner, attr, _)::Float64
 end
 
+#=
+    MOI.SolveTimeSec
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.SolveTimeSec)
     _throw_if_optimize_in_progress(model, attr)
     return model.cached_solution.solve_time
 end
 
+#=
+    MOI.SimplexIterations
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.SimplexIterations)
     _throw_if_optimize_in_progress(model, attr)
     return @_invoke Lib.XPRSgetintattrib(
@@ -3662,16 +3580,28 @@ function MOI.get(model::Optimizer, attr::MOI.SimplexIterations)
     )::Int
 end
 
+#=
+    MOI.BarrierIterations
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.BarrierIterations)
     _throw_if_optimize_in_progress(model, attr)
     return @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_BARITER, _)::Int
 end
 
+#=
+    MOI.NodeCount
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.NodeCount)
     _throw_if_optimize_in_progress(model, attr)
     return @_invoke Lib.XPRSgetintattrib(model.inner, Lib.XPRS_NODES, _)::Int
 end
 
+#=
+    MOI.RelativeGap
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.RelativeGap)
     _throw_if_optimize_in_progress(model, attr)
     BESTBOUND = MOI.get(model, MOI.ObjectiveBound())
@@ -3679,12 +3609,21 @@ function MOI.get(model::Optimizer, attr::MOI.RelativeGap)
     return abs(MIPOBJVAL - BESTBOUND) / max(abs(BESTBOUND), abs(MIPOBJVAL))
 end
 
+#=
+    MOI.DualObjectiveValue
+=#
+
+# TODO(odow): this is wrong
 function MOI.get(model::Optimizer, attr::MOI.DualObjectiveValue)
     _throw_if_optimize_in_progress(model, attr)
     MOI.check_result_index_bounds(model, attr)
     return MOI.get(model, MOI.ObjectiveValue(attr.result_index))
 end
 
+#=
+    MOI.ResultCount
+=#
+
 function MOI.get(model::Optimizer, attr::MOI.ResultCount)
     _throw_if_optimize_in_progress(model, attr)
     if model.cached_solution === nothing
@@ -3693,20 +3632,29 @@ function MOI.get(model::Optimizer, attr::MOI.ResultCount)
         return 1
     elseif model.cached_solution.has_primal_certificate
         return 1
-    else
-        return (model.cached_solution.has_feasible_point) ? 1 : 0
     end
+    return model.cached_solution.has_feasible_point ? 1 : 0
 end
 
-function MOI.get(model::Optimizer, ::MOI.Silent)
-    return model.log_level == 0
-end
+#=
+    MOI.Silent
+=#
+
+MOI.supports(::Optimizer, ::MOI.Silent) = true
+
+MOI.get(model::Optimizer, ::MOI.Silent) = model.log_level == 0
 
 function MOI.set(model::Optimizer, ::MOI.Silent, flag::Bool)
     MOI.set(model, MOI.RawOptimizerAttribute("OUTPUTLOG"), ifelse(flag, 0, 1))
     return
 end
 
+#=
+    MOI.NumberOfThreads
+=#
+
+MOI.supports(::Optimizer, ::MOI.NumberOfThreads) = true
+
 function MOI.get(model::Optimizer, ::MOI.NumberOfThreads)
     return Int(MOI.get(model, MOI.RawOptimizerAttribute("THREADS")))
 end
@@ -3715,6 +3663,12 @@ function MOI.set(model::Optimizer, ::MOI.NumberOfThreads, x::Int)
     return MOI.set(model, MOI.RawOptimizerAttribute("THREADS"), x)
 end
 
+#=
+    MOI.Name
+=#
+
+MOI.supports(::Optimizer, ::MOI.Name) = true
+
 function MOI.get(model::Optimizer, ::MOI.Name)
     return model.name
 end
@@ -3725,12 +3679,37 @@ function MOI.set(model::Optimizer, ::MOI.Name, name::String)
     return
 end
 
+#=
+    MOI.RawSolver
+=#
+
+MOI.get(model::Optimizer, ::MOI.RawSolver) = model.inner
+
+#=
+    MOI.NumberOfVariables
+=#
+
 MOI.get(model::Optimizer, ::MOI.NumberOfVariables) = length(model.variable_info)
+
+#=
+    MOI.ListOfVariableIndices
+=#
+
 function MOI.get(model::Optimizer, ::MOI.ListOfVariableIndices)
     return sort!(collect(keys(model.variable_info)); by = x -> x.value)
 end
 
-MOI.get(model::Optimizer, ::MOI.RawSolver) = model.inner
+#=
+    MOI.VariablePrimalStart
+=#
+
+function MOI.supports(
+    ::Optimizer,
+    ::MOI.VariablePrimalStart,
+    ::Type{MOI.VariableIndex},
+)
+    return true
+end
 
 function MOI.set(
     model::Optimizer,
@@ -3751,14 +3730,6 @@ function MOI.get(
     return _info(model, x).start
 end
 
-function MOI.supports(
-    ::Optimizer,
-    ::MOI.VariablePrimalStart,
-    ::Type{MOI.VariableIndex},
-)
-    return true
-end
-
 function MOI.get(model::Optimizer, ::MOI.NumberOfConstraints{F,S}) where {F,S}
     # TODO: this could be more efficient.
     return length(MOI.get(model, MOI.ListOfConstraintIndices{F,S}()))
@@ -3917,17 +3888,14 @@ function MOI.modify(
 ) where {S}
     nels = length(cis)
     @assert nels == length(chgs)
-
     rows = Vector{Cint}(undef, nels)
     cols = Vector{Cint}(undef, nels)
     coefs = Vector{Float64}(undef, nels)
-
     for i in 1:nels
         rows[i] = Cint(_info(model, cis[i]).row - 1)
         cols[i] = Cint(_info(model, chgs[i].variable).column - 1)
         coefs[i] = chgs[i].new_coefficient
     end
-
     @checked Lib.XPRSchgmcoef(model.inner, Cint(nels), rows, cols, coefs)
     return
 end
@@ -3958,12 +3926,10 @@ function MOI.modify(
     nels = length(chgs)
     cols = Vector{Cint}(undef, nels)
     coefs = Vector{Float64}(undef, nels)
-
     for i in 1:nels
         cols[i] = _info(model, chgs[i].variable).column - 1
         coefs[i] = chgs[i].new_coefficient
     end
-
     @checked Lib.XPRSchgobj(model.inner, Cint(length(coefs)), cols, coefs)
     model.is_objective_set = true
     return
@@ -4117,24 +4083,19 @@ function MOI.get(
     ::MOI.ConstraintBasisStatus,
     c::MOI.ConstraintIndex{MOI.ScalarAffineFunction{Float64},S},
 ) where {S<:SCALAR_SETS}
-    row = _info(model, c).row
-    basis_status = model.basis_status
-    if basis_status == nothing
-        _generate_basis_status(model::Optimizer)
-        basis_status = model.basis_status
+    if model.basis_status == nothing
+        _generate_basis_status(model)
     end
-    cstatus = basis_status.con_status
-    cbasis = cstatus[row]
+    cbasis = model.basis_status.con_status[_info(model, c).row]
     if cbasis == 1
         return MOI.BASIC
     elseif cbasis == 0
         return MOI.NONBASIC
     elseif cbasis == 2
         return MOI.NONBASIC
-    elseif cbasis == 3
-        return MOI.SUPER_BASIC
     else
-        error("CBasis value of $(cbasis) isn't defined.")
+        @assert cbasis == 3
+        return MOI.SUPER_BASIC
     end
 end
 
@@ -4246,7 +4207,7 @@ function MOI.add_constraint(
     )
     @checked Lib.XPRSaddqmatrix(
         model.inner,
-        Xpress.n_constraints(model.inner) - 1,
+        n_constraints(model.inner) - 1,
         Cint(length(I)),
         I,
         I,
@@ -4338,7 +4299,7 @@ function MOI.add_constraint(
     )
     @checked Lib.XPRSaddqmatrix(
         model.inner,
-        Xpress.n_constraints(model.inner) - 1,
+        n_constraints(model.inner) - 1,
         length(I),
         I,
         J,
@@ -4589,7 +4550,6 @@ function getfirstiis(model::Optimizer)
     iismode = Cint(1)
     status_code = Ref{Cint}(0)
     @checked Lib.XPRSiisfirst(model.inner, iismode, status_code)
-
     if status_code[] == 1
         # The problem is actually feasible.
         return IISData(
@@ -4615,11 +4575,9 @@ function getfirstiis(model::Optimizer)
             UInt8[],
         )
     end
-
     # XPRESS' API works in two steps: first, retrieve the sizes of the arrays to
     # retrieve; then, the user is expected to allocate the needed memory,
     # before asking XPRESS to fill it.
-
     num = Cint(1)
     rownumber = Ref{Cint}(0)
     colnumber = Ref{Cint}(0)
@@ -4637,7 +4595,6 @@ function getfirstiis(model::Optimizer)
         C_NULL,
         C_NULL,
     )
-
     nrows = rownumber[]
     ncols = colnumber[]
     miisrow = Vector{Cint}(undef, nrows)
@@ -4658,7 +4615,6 @@ function getfirstiis(model::Optimizer)
         C_NULL,
         C_NULL,
     )
-
     return IISData(
         status_code[],
         true,
@@ -4683,6 +4639,7 @@ function _ensure_conflict_computed(model::Optimizer)
             "In case the model is modified, the computed conflict will not be purged.",
         )
     end
+    return
 end
 
 function MOI.get(model::Optimizer, ::MOI.ConflictStatus)
@@ -4697,14 +4654,9 @@ function MOI.get(model::Optimizer, ::MOI.ConflictStatus)
         # stat == 2 -> error
         # stat == 3 -> timeout
         return MOI.NO_CONFLICT_FOUND
-        # return error("IIS failed internally.")
     end
 end
 
-function MOI.supports(::Optimizer, ::MOI.ConflictStatus)
-    return true
-end
-
 function MOI.get(
     model::Optimizer,
     ::MOI.ConstraintConflictStatus,
@@ -4714,8 +4666,10 @@ function MOI.get(
     },
 )
     _ensure_conflict_computed(model)
-    return (_info(model, index).row - 1) in model.conflict.miisrow ?
-           MOI.IN_CONFLICT : MOI.NOT_IN_CONFLICT
+    if _info(model, index).row - 1 in model.conflict.miisrow
+        return MOI.IN_CONFLICT
+    end
+    return MOI.NOT_IN_CONFLICT
 end
 
 col_type_char(::Type{MOI.LessThan{Float64}}) = 'U'
@@ -4726,6 +4680,7 @@ col_type_char(::Type{MOI.ZeroOne}) = 'B'
 col_type_char(::Type{MOI.Integer}) = 'I'
 col_type_char(::Type{MOI.Semicontinuous{Float64}}) = 'S'
 col_type_char(::Type{MOI.Semiinteger{Float64}}) = 'R'
+
 function MOI.get(
     model::Optimizer,
     ::MOI.ConstraintConflictStatus,
@@ -4744,6 +4699,7 @@ function MOI.get(
     end
     return MOI.NOT_IN_CONFLICT
 end
+
 function MOI.get(
     model::Optimizer,
     ::MOI.ConstraintConflictStatus,
@@ -4782,55 +4738,28 @@ function MOI.get(
     end
     return MOI.NOT_IN_CONFLICT
 end
-function MOI.supports(
-    ::Optimizer,
-    ::MOI.ConstraintConflictStatus,
-    ::Type{MOI.ConstraintIndex{<:MOI.VariableIndex,<:SCALAR_SETS}},
-)
-    return true
-end
-
-function MOI.supports(
-    ::Optimizer,
-    ::MOI.ConstraintConflictStatus,
-    ::Type{
-        MOI.ConstraintIndex{
-            <:MOI.ScalarAffineFunction,
-            <:Union{MOI.LessThan,MOI.GreaterThan,MOI.EqualTo},
-        },
-    },
-)
-    return true
-end
-
-include("MOI_callbacks.jl")
 
-function extension(str::String)
-    try
-        match(r"\.[A-Za-z0-9]+$", str).match
-    catch
-        ""
-    end
-end
+#=
+    MOI.write_to_file
+=#
 
 function MOI.write_to_file(model::Optimizer, name::String)
-    ext = extension(name)
-    if ext == ".lp"
-        @checked Lib.XPRSwriteprob(model.inner, name, "l")
-    elseif ext == ".mps"
-        @checked Lib.XPRSwriteprob(model.inner, name, "")
-    else
-        @checked Lib.XPRSwriteprob(model.inner, name, "l")
-    end
+    flag = endswith(name, ".mps") ? "" : "l"
+    @checked Lib.XPRSwriteprob(model.inner, name, flag)
+    return
 end
 
-function _pass_names_to_solver(model::Xpress.Optimizer; warn = true)
+#=
+    _pass_names_to_solver
+=#
+
+function _pass_names_to_solver(model::Optimizer; warn = true)
     _pass_variable_names_to_solver(model; warn = warn)
     _pass_constraint_names_to_solver(model; warn = warn)
-    return nothing
+    return
 end
 
-function _pass_variable_names_to_solver(model::Xpress.Optimizer; warn = true)
+function _pass_variable_names_to_solver(model::Optimizer; warn = true)
     NAMELENGTH = 64
     n_variables = length(model.variable_info)
     if n_variables == 0
@@ -4866,7 +4795,7 @@ function _pass_variable_names_to_solver(model::Xpress.Optimizer; warn = true)
     return nothing
 end
 
-function _pass_constraint_names_to_solver(model::Xpress.Optimizer; warn = true)
+function _pass_constraint_names_to_solver(model::Optimizer; warn = true)
     NAMELENGTH = 64
     n_constraints = length(model.affine_constraint_info)
     if n_constraints == 0
@@ -4975,11 +4904,11 @@ end
 MOI.supports(::Optimizer, ::MOI.RelativeGapTolerance) = true
 
 function MOI.get(model::Optimizer, ::MOI.RelativeGapTolerance)
-    return Xpress.getcontrol(model.inner, Lib.XPRS_MIPRELSTOP)
+    return getcontrol(model.inner, Lib.XPRS_MIPRELSTOP)
 end
 
 function MOI.set(model::Optimizer, ::MOI.RelativeGapTolerance, value::Float64)
-    Xpress.setcontrol!(model.inner, Lib.XPRS_MIPRELSTOP, value)
+    setcontrol!(model.inner, Lib.XPRS_MIPRELSTOP, value)
     return
 end
 
@@ -4990,10 +4919,10 @@ end
 MOI.supports(::Optimizer, ::MOI.AbsoluteGapTolerance) = true
 
 function MOI.get(model::Optimizer, ::MOI.AbsoluteGapTolerance)
-    return Xpress.getcontrol(model.inner, Lib.XPRS_MIPABSSTOP)
+    return getcontrol(model.inner, Lib.XPRS_MIPABSSTOP)
 end
 
 function MOI.set(model::Optimizer, ::MOI.AbsoluteGapTolerance, value::Float64)
-    Xpress.setcontrol!(model.inner, Lib.XPRS_MIPABSSTOP, value)
+    setcontrol!(model.inner, Lib.XPRS_MIPABSSTOP, value)
     return
 end
diff --git a/src/Xpress.jl b/src/Xpress.jl
index ee0e5e75..bbca64d0 100644
--- a/src/Xpress.jl
+++ b/src/Xpress.jl
@@ -56,6 +56,7 @@ function initialize()
 end
 
 include("MOI/MOI_wrapper.jl")
+include("MOI/MOI_callbacks.jl")
 
 function __init__()
     if !haskey(ENV, "XPRESS_JL_NO_AUTO_INIT") &&