add note on comparing types
@@ -218,6 +218,9 @@ Flecs is an Entity Component System, and it is important to realize that ECS is
### Minimize the usage of ecs_get, ecs_set
An ECS framework is only as efficient as the way it is used, and the most inefficient way of accomplishing something in an ECS framework is by extensively using `ecs_get` and `ecs_set`. This always requires the framework to do lookups in the set of components the entity has, which is quite slow. It also is an indication that code relies to much on individual entities, whereas in ECS it is more common practice to write code that operates on entity collections. The preferred way to do this in Flecs is with _systems_, which can access components directly, without requiring a lookup.
+### Never compare entity types with anything
+The type (of type `ecs_type_t`) of an entity is a handle that uniquely identifies the components an entity has. Even though the API provides a function to get the type of a specific entity (`ecs_get_type`) it is big code smell to compare this type with anything other than for debugging. In ECS applications the type of an entity may change any moment, and directly comparing the entity type is almost guaranteed to break at some point. Instead, use `ecs_has` if you want to check whether an entity has a component (or set of components, by providing a type to `ecs_has`).
+
### Write code in systems
If you find yourself writing lots of code in the main loop of your application that is not executed in a system, it could be a sign of code smell. Logic in ECS runs best when it is part of a system. A system ensures that your code has a clear interface, which makes it easy to reuse the system in other applications. Flecs adds additional benefits to using systems like being able to automatically or manually (remotely!) enable/disable them, and schedule them to run on different threads.
