Add doc comments for Entity.get / getRef / getMut

src/entity.zig

@@ -301,16 +301,34 @@ pub fn Entity(comptime ctx: anytype) type {
             c.ecs_remove_id(self.world.raw, self.raw, ecs_id);
         }
 
+        /// Gets a value copy of a component.
+        /// If the component does not exist, returns null.
         pub fn get(self: Self, comptime T: type) ?T {
             return if (getRef(self, T)) |p| p.* else null;
         }
 
+        /// Gets an immutable pointer to a component.
+        /// If the component does not exist, returns null.
+        ///
+        /// The returned pointer may become invalid after calling other Flecs
+        /// functions, notably when an `Entity` moves to another table caused
+        /// by adding or removing other components.
         pub fn getRef(self: Self, comptime T: type) ?*const T {
             const id = Context.lookup(T).*;
             const ptr = c.ecs_get_id(self.world.raw, self.raw, id);
             return @alignCast(@ptrCast(ptr));
         }
 
+        /// Get a mutable pointer to a component.
+        /// If the component did not yet exist, it will be added.
+        ///
+        /// The returned pointer may become invalid after calling other Flecs
+        /// functions, notably when an `Entity` moves to another table caused
+        /// by adding or removing other components.
+        ///
+        /// If `getMut` is called when the world is in deferred / readonly
+        /// mode, and the component does not yet exist, it will return a
+        /// pointer to a temp storage.
         pub fn getMut(self: Self, comptime T: type) *T {
             const id = Context.lookup(T).*;
             const ptr = c.ecs_get_mut_id(self.world.raw, self.raw, id);