Support config domains with either method or attribute domain_name

pyomo/common/config.py

@@ -1134,7 +1134,11 @@ def _domain_name(domain):
     if domain is None:
         return ""
     elif hasattr(domain, 'domain_name'):
-        return domain.domain_name()
+        dn = domain.domain_name
+        if hasattr(dn, '__call__'):
+            return dn()
+        else:
+            return dn
     elif domain.__class__ is type:
         return domain.__name__
     elif inspect.isfunction(domain):

pyomo/common/tests/test_config.py

@@ -3265,6 +3265,41 @@ def __init__(
             OUT.getvalue().replace('null', 'None'),
         )
 
+    def test_domain_name(self):
+        cfg = ConfigDict()
+
+        cfg.declare('none', ConfigValue())
+        self.assertEqual(cfg.get('none').domain_name(), '')
+
+        def fcn(val):
+            return val
+
+        cfg.declare('fcn', ConfigValue(domain=fcn))
+        self.assertEqual(cfg.get('fcn').domain_name(), 'fcn')
+
+        fcn.domain_name = 'custom fcn'
+        self.assertEqual(cfg.get('fcn').domain_name(), 'custom fcn')
+
+        class functor:
+            def __call__(self, val):
+                return val
+
+        cfg.declare('functor', ConfigValue(domain=functor()))
+        self.assertEqual(cfg.get('functor').domain_name(), 'functor')
+
+        class cfunctor:
+            def __call__(self, val):
+                return val
+
+            def domain_name(self):
+                return 'custom functor'
+
+        cfg.declare('cfunctor', ConfigValue(domain=cfunctor()))
+        self.assertEqual(cfg.get('cfunctor').domain_name(), 'custom functor')
+
+        cfg.declare('type', ConfigValue(domain=int))
+        self.assertEqual(cfg.get('type').domain_name(), 'int')
+
 
 if __name__ == "__main__":
     unittest.main()