Shorter syntax from @YannickJadoul

Author: henryiii

include/pybind11/pybind11.h

@@ -1378,13 +1378,12 @@ template <typename Type> class enum_ : public class_<Type> {
         }, return_value_policy::copy);
         def(init([](Scalar i) { return static_cast<Type>(i); }));
         def(init([name, m_entries_ptr](std::string value) -> Type {
-            for (const auto &kv : reinterpret_borrow<dict>(m_entries_ptr)) {
-                std::string key = pybind11::cast<pybind11::str>(kv.first);
-                if (value == key) {
-                    return pybind11::cast<Type>(kv.second);
-                }
-            }
-            throw value_error("\"" + value + "\" is not a valid value for enum type " + name);
+            pybind11::dict values = reinterpret_borrow<pybind11::dict>(m_entries_ptr);
+            pybind11::str key = pybind11::str(value);
+            if (values.contains(key))
+                return pybind11::cast<Type>(values[key]);
+            else
+                throw value_error("\"" + value + "\" is not a valid value for enum type " + name);
         }));
         def("__int__", [](Type value) { return (Scalar) value; });
         #if PY_MAJOR_VERSION < 3