Merge pull request #32506 from mantidproject/configservice_get

New method "get" for the ConfigService class

Framework/PythonInterface/mantid/kernel/src/Exports/ConfigService.cpp

@@ -50,6 +50,16 @@ const InstrumentInfo &getInstrument(ConfigServiceImpl &self, const object &name
     return self.getInstrument(ExtractStdString(name)());
 }
 
+/// duck typing emulating dict.get method
+std::string getStringUsingCacheElseDefault(ConfigServiceImpl &self, const std::string &key,
+                                           const std::string &defaultValue) {
+  std::vector<std::string> keys = self.keys();
+  if (self.hasProperty(key))
+    return self.getString(key, true);
+  else
+    return defaultValue;
+}
+
 GNU_DIAG_OFF("unused-local-typedef")
 // Ignore -Wconversion warnings coming from boost::python
 // Seen with GCC 7.1.1 and Boost 1.63.0
@@ -134,6 +144,12 @@ void export_ConfigService() {
       .def("keys", &ConfigServiceImpl::keys, arg("self"))
 
       // Treat this as a dictionary
+      .def("get", &getStringUsingCache, (arg("self"), arg("key")),
+           "get the string value of a property; return empty string value if the property "
+           "is not found in the configuration")
+      .def("get", &getStringUsingCacheElseDefault, (arg("self"), arg("key")), arg("default"),
+           "get the string value of a property; return a default string value if the property "
+           "is not found in the configuration")
       .def("__getitem__", &getStringUsingCache, (arg("self"), arg("key")))
       .def("__setitem__", &ConfigServiceImpl::setString, (arg("self"), arg("key"), arg("value")))
       .def("__contains__", &ConfigServiceImpl::hasProperty, (arg("self"), arg("key")))

Framework/PythonInterface/test/python/mantid/kernel/ConfigServiceTest.py

@@ -64,17 +64,29 @@ class ConfigServiceTest(unittest.TestCase):
         self.assertRaises(RuntimeError, config.getInstrument, "MadeUpInstrument")
 
     def test_service_acts_like_dictionary(self):
+        dictcall = config.get("property_not_found")
+        self.assertEqual(dictcall, "")
+
         test_prop = "projectRecovery.secondsBetween"
         self.assertTrue(config.hasProperty(test_prop))
         dictcall = config[test_prop]
         fncall = config.getString(test_prop)
+
+        # Use brackets to retrieve a value
+        dictcall = config[test_prop]
         self.assertEqual(dictcall, fncall)
         self.assertNotEqual(config[test_prop], "")
 
+        # Use "get" to retrieve a value or a default
+        dictcall = config.get(test_prop, "other")
+        self.assertEqual(dictcall, fncall)
+        dictcall = config.get("property_not_found", "default_alternative")
+        self.assertEqual(dictcall, "default_alternative")
+
         old_value = fncall
         config.setString(test_prop, "1")
         self.assertEqual(config.getString(test_prop), "1")
-        config[test_prop] =  "2"
+        config[test_prop] = "2"
         self.assertEqual(config.getString(test_prop), "2")
 
         config.setString(test_prop, old_value)