refactor: error message so parametric expression error easier to appear

Author: MilesCranmer

src/DynamicExpressions.jl

@@ -66,9 +66,9 @@ import .NodeModule:
 @reexport import .EvaluationHelpersModule
 @reexport import .ExtensionInterfaceModule: node_to_symbolic, symbolic_to_node
 @reexport import .RandomModule: NodeSampler
-@reexport import .ExpressionModule:
-    AbstractExpression, Expression, with_tree, default_node_type, node_type
-import .ExpressionModule: get_tree, get_operators, get_variable_names, Metadata
+@reexport import .ExpressionModule: AbstractExpression, Expression, with_tree
+import .ExpressionModule:
+    get_tree, get_operators, get_variable_names, Metadata, default_node_type, node_type
 @reexport import .ParseModule: @parse_expression, parse_expression
 import .ParseModule: parse_leaf
 @reexport import .ParametricExpressionModule: ParametricExpression, ParametricNode

src/ParametricExpression.jl

@@ -226,12 +226,22 @@ function Base.convert(::Type{Node}, ex::ParametricExpression{T}) where {T}
         Node{T},
     )
 end
-function eval_tree_array(
-    ::ParametricExpression{T}, ::AbstractMatrix{T}, operators; kws...
+#! format: off
+function (ex::ParametricExpression)(X::AbstractMatrix, operators=nothing; kws...)
+    return eval_tree_array(ex, X, operators; kws...)  # Will error
+end
+function eval_tree_array(::ParametricExpression{T}, ::AbstractMatrix{T}, operators=nothing; kws...) where {T}
+    return error("Incorrect call. You must pass the `classes::Vector` argument when calling `eval_tree_array`.")
+end
+#! format: on
+function (ex::ParametricExpression)(
+    X::AbstractMatrix{T}, classes::AbstractVector{<:Integer}, operators=nothing; kws...
 ) where {T}
-    return error(
-        "Incorrect call. You must pass the `classes::Vector` argument when calling `eval_tree_array`.",
-    )
+    (output, flag) = eval_tree_array(ex, X, classes, operators; kws...)  # Will error
+    if !flag
+        output .= NaN
+    end
+    return output
 end
 function eval_tree_array(
     ex::ParametricExpression{T},

test/test_parametric_expression.jl

@@ -37,6 +37,11 @@ end
 
     # Then, with different classes
     @test ex(X, [1, 2, 2, 3, 1]) ≈ [1.0, 3.0, 2.0, 2.0, 1.0]
+
+    # Helpful error if we use it incorrectly
+    if VERSION >= v"1.9"
+        @test_throws "Incorrect call. You must pass" ex(X)
+    end
 end
 
 @testitem "2 parameters, 2 variables" begin
@@ -162,6 +167,22 @@ end
     @test copy(ex) == ex
 end
 
+@testitem "Passing node within ParametricExpression parsing" begin
+    using DynamicExpressions
+
+    tree = ParametricNode{Float32}()
+    tree.degree = 0
+    tree.constant = true
+    tree.val = 1.5
+    ex = parse_expression(
+        :($tree);
+        expression_type=ParametricExpression,
+        parameters=Float32[;;],
+        parameter_names=nothing,
+    )
+    @test ex.tree == tree
+end
+
 @testitem "Parametric expression conversion" begin
     using DynamicExpressions
 
@@ -173,9 +194,7 @@ end
         extra_metadata = (; parameters=Float32[;;], parameter_names=nothing)
     )
     ex = @parse_expression(
-        x1 + 1.5f0,
-        binary_operators = [+, -, *],
-        variable_names = ["x1"],
+        x1 + 1.5f0, binary_operators = [+, -, *], variable_names = ["x1"],
     )
 
     @test pex.tree isa ParametricNode{Float32}