Split out fn from print_evaluate

mathics/eval/tracing.py

@@ -17,23 +17,20 @@
 hook_exit_fn: Optional[Callable] = None
 
 
-def print_evaluate(expr, evaluation, status: str, fn: Callable, orig_expr=None):
-    """
-    Called from a decorated Python @trace_evaluate .evaluate()
-    method when TraceActivate["evaluate" -> True]
+def skip_trivial_evaluation(expr, status: str, orig_expr=None) -> bool:
     """
+    Look for uninteresting evaluations that we should avoid showing
+    printing tracing status or stopping in a debugger.
 
-    if evaluation.definitions.timing_trace_evaluation:
-        evaluation.print_out(time.time() - evaluation.start_time)
-
-    # Test and dispose of various situations where showing information
-    # is pretty useless: evaluating a Symbol is the Symbol.
-    # Showing the return value of a ListExpression literal is
-    # also useless.
+    This includes things like:
+    * the evaluation is a literal that evaluates to the same thing,
+    * evaluating a Symbol which the Symbol.
+    * Showing the return value of a ListExpression literal
+    """
     from mathics.core.symbols import Symbol, SymbolConstant
 
     if isinstance(expr, Symbol) and not isinstance(expr, SymbolConstant):
-        return
+        return True
 
     if (
         status == "Returning"
@@ -42,11 +39,26 @@ def print_evaluate(expr, evaluation, status: str, fn: Callable, orig_expr=None):
         and hasattr(orig_expr, "is_literal")
         and orig_expr.is_literal
     ):
-        return
+        return True
 
     if orig_expr == expr:
         # If the two expressions are the same, there is no point in
         # repeating the output.
+        return True
+
+    return False
+
+
+def print_evaluate(expr, evaluation, status: str, fn: Callable, orig_expr=None):
+    """
+    Called from a decorated Python @trace_evaluate .evaluate()
+    method when TraceActivate["evaluate" -> True]
+    """
+
+    if evaluation.definitions.timing_trace_evaluation:
+        evaluation.print_out(time.time() - evaluation.start_time)
+
+    if skip_trivial_evaluation(expr, status, orig_expr):
         return
 
     indents = "  " * evaluation.recursion_depth
@@ -108,7 +120,7 @@ def wrapper(expr, evaluation) -> Any:
         if not skip_call:
             result = func(expr, evaluation)
             if trace_evaluate_on_return is not None and not was_boxing:
-                trace_evaluate_on_return(result, evaluation, "Returning", func, expr)
+                trace_evaluate_on_return(result, evaluation, "Returning", expr, result)
             evaluation.is_boxing = was_boxing
         return result