Type stability for variable names

Author: MilesCranmer

src/OperatorEnumConstruction.jl

@@ -27,7 +27,7 @@ const ALREADY_DEFINED_UNARY_OPERATORS = (;
 const ALREADY_DEFINED_BINARY_OPERATORS = (;
     operator_enum=Dict{Function,Bool}(), generic_operator_enum=Dict{Function,Bool}()
 )
-const LATEST_VARIABLE_NAMES = Ref{Union{Nothing,Vector{String}}}(nothing)
+const LATEST_VARIABLE_NAMES = Ref{Vector{String}}(String[])
 
 function Base.show(io::IO, tree::Node)
     latest_operators_type = LATEST_OPERATORS_TYPE.x

test/test_print.jl

@@ -100,14 +100,18 @@ end
 end
 
 @testset "Test variable names" begin
-    operators = OperatorEnum(;
-        binary_operators=[+, *, /, -], unary_operators=[cos, sin],
-    )
+    operators = OperatorEnum(; binary_operators=[+, *, /, -], unary_operators=[cos, sin])
     @extend_operators operators
     x1, x2, x3 = [Node(Float64; feature=i) for i in 1:3]
-    DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x = ["k1", "k2", "k3"]
+    DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x = [
+        "k1", "k2", "k3"
+    ]
     tree = x1 * x2 + x3
     @test string(tree) == "((k1 * k2) + k3)"
-    DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x = nothing
+    empty!(DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x)
     @test string(tree) == "((x1 * x2) + x3)"
+    # Check if we can pass the wrong number of variable names:
+    DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x = ["k1"]
+    @test string(tree) == "((k1 * x2) + x3)"
+    empty!(DynamicExpressions.OperatorEnumConstructionModule.LATEST_VARIABLE_NAMES.x)
 end