add var decl convenience function

wright · wright · commit 13956c998450 · 2019-11-14T14:50:37.000Z
diff --git a/src/Datalog.h b/src/Datalog.h
@@ -40,6 +40,18 @@ struct Variable : optional<T>
 	}
 };
 
+// TODO: use auto more for return type of functions
+
+template<typename T>
+Variable<T>* var() {
+	return new Variable<T>();
+}
+
+template<typename T>
+void deleteVar(Variable<T>* v) {
+	delete v;
+}
+
 template <typename T>
 static void unbind(const T& t) {}
 
diff --git a/tests/types_test.cpp b/tests/types_test.cpp
@@ -33,8 +33,8 @@ bool test1()
         {thor, god}};
 
     // Rule
-    Variable<Name> x;
-    auto rule1 = rule(atom<Mortal>(&x), atom<Thing>(&x, person));
+    auto x = var<Name>();
+    auto rule1 = rule(atom<Mortal>(x), atom<Thing>(x, person));
 
     State<Thing, Mortal> state{things, {}};
 
@@ -45,6 +45,8 @@ bool test1()
     state = fixPoint(rules, state);
     cout << "after = " << state << endl;
 
+    deleteVar(x);
+
     return true;
 }
 
