Remove object references from model.ext[:miplearn]

src/solvers/macros.jl

@@ -6,10 +6,10 @@ function init_miplearn_ext(model)::Dict
     if :miplearn ∉ keys(model.ext)
         model.ext[:miplearn] = Dict{Symbol, Any}()
         model.ext[:miplearn][:instance_features] = [0.0]
-        model.ext[:miplearn][:variable_features] = Dict{VariableRef, Vector{Float64}}()
-        model.ext[:miplearn][:variable_categories] = Dict{VariableRef, String}()
-        model.ext[:miplearn][:constraint_features] = Dict{ConstraintRef, Vector{Float64}}()
-        model.ext[:miplearn][:constraint_categories] = Dict{ConstraintRef, String}()
+        model.ext[:miplearn][:variable_features] = Dict{AbstractString, Vector{Float64}}()
+        model.ext[:miplearn][:variable_categories] = Dict{AbstractString, String}()
+        model.ext[:miplearn][:constraint_features] = Dict{AbstractString, Vector{Float64}}()
+        model.ext[:miplearn][:constraint_categories] = Dict{AbstractString, String}()
     end
     return model.ext[:miplearn]
 end
@@ -24,28 +24,32 @@ end
 
 function set_features!(v::VariableRef, f::Array{Float64})::Nothing
     ext = init_miplearn_ext(v.model)
-    ext[:variable_features][v] = f
+    n = _get_and_check_name(v)
+    ext[:variable_features][n] = f
     return
 end
 
 
 function set_category!(v::VariableRef, category::String)::Nothing
     ext = init_miplearn_ext(v.model)
-    ext[:variable_categories][v] = category
+    n = _get_and_check_name(v)
+    ext[:variable_categories][n] = category
     return
 end
 
 
 function set_features!(c::ConstraintRef, f::Array{Float64})::Nothing
     ext = init_miplearn_ext(c.model)
-    ext[:constraint_features][c] = f
+    n = _get_and_check_name(c)
+    ext[:constraint_features][n] = f
     return
 end
 
 
 function set_category!(c::ConstraintRef, category::String)::Nothing
     ext = init_miplearn_ext(c.model)
-    ext[:constraint_categories][c] = category
+    n = _get_and_check_name(c)
+    ext[:constraint_categories][n] = category
     return
 end
 
@@ -63,6 +67,15 @@ macro category(obj, category)
     end
 end
 
+function _get_and_check_name(obj)
+    n = name(obj)
+    length(n) > 0 || error(
+        "Features and categories can only be assigned to variables and " *
+        "constraints that have names. Unnamed model element detected."
+    )
+    return n
+end
+
 
 export @feature,
        @category