Merge pull request Pyomo#1946 from michaelbynum/eval

reduce errors logged with value when exception is False

pyomo/core/expr/visitor.py

@@ -929,6 +929,9 @@ def accept(node, data, child_result, child_idx):
 
 class _EvaluationVisitor(ExpressionValueVisitor):
 
+    def __init__(self, exception):
+        self.exception = exception
+
     def visit(self, node, values):
         """ Visit nodes that have been expanded """
         return node._apply_operation(values)
@@ -946,9 +949,9 @@ def visiting_potential_leaf(self, node):
             return False, None
 
         if node.is_numeric_type():
-            return True, value(node)
+            return True, value(node, exception=self.exception)
         elif node.is_logical_type():
-            return True, value(node)
+            return True, value(node, exception=self.exception)
         else:
             return True, node
 
@@ -1036,7 +1039,7 @@ def evaluate_expression(exp, exception=True, constant=False):
     if constant:
         visitor = _EvaluateConstantExpressionVisitor()
     else:
-        visitor = _EvaluationVisitor()
+        visitor = _EvaluationVisitor(exception=exception)
     try:
         return visitor.dfs_postorder_stack(exp)
 

pyomo/core/tests/unit/test_numeric_expr.py

@@ -22,6 +22,8 @@
 
 from filecmp import cmp
 import pyomo.common.unittest as unittest
+from pyomo.common.log import LoggingIntercept
+from io import StringIO
 
 from pyomo.environ import ConcreteModel, AbstractModel, RangeSet, Var, Param, Set, Constraint, ConstraintList, Expression, Objective, Reals, ExternalFunction, PositiveReals, log10, exp, floor, ceil, log, cos, sin, tan, acos, asin, atan, sinh, cosh, tanh, acosh, asinh, atanh, sqrt, value, quicksum, sum_product, is_fixed, is_constant
 from pyomo.kernel import variable, expression, objective
@@ -5244,5 +5246,17 @@ def con_rule(model):
         self.assertEqual(polynomial_degree(m.c1.body), 1)
 
 
+class TestEvaluation(unittest.TestCase):
+    def test_log_error(self):
+        m = ConcreteModel()
+        m.x = Var()
+        e = m.x**2
+        os = StringIO()
+        with LoggingIntercept(os, 'pyomo'):
+            e_val = value(e, exception=False)
+            self.assertIsNone(e_val)
+        self.assertEqual(os.getvalue(), '')
+
+
 if __name__ == "__main__":
     unittest.main()