Provide static bool to check for user data support

include/podio/UserDataCollection.h

@@ -32,13 +32,19 @@ using SupportedUserDataTypes =
     std::tuple<float, double, int8_t, int16_t, int32_t, int64_t, uint8_t, uint16_t, uint32_t, uint64_t>;
 
 /**
- * Alias template to be used to enable template specializations only for the
- * types listed in the SupportedUserDataTypes list or if they are components
- * that were generated by podio
+ * Static bool for determining whether a type T is a supported user data type.
+ * Effectively boils down to being listed in SupportedUserDataTypes or being a
+ * component of an EDM generated by podio.
  */
 template <typename T>
-using EnableIfSupportedUserType =
-    std::enable_if_t<detail::isInTuple<T, SupportedUserDataTypes> || detail::isComponent<T>>;
+constexpr static bool isSupportedUserDataType = detail::isInTuple<T, SupportedUserDataTypes> || detail::isComponent<T>;
+
+/**
+ * Alias template to be used to enable template specializations only for types
+ * that are actually supported user data types
+ */
+template <typename T>
+using EnableIfSupportedUserType = std::enable_if_t<isSupportedUserDataType<T>>;
 
 /** helper template to provide readable type names for basic types with macro PODIO_ADD_USER_TYPE(type)
  */