If you are inside a class and want to call an instance method that belong to the same class you can call it by using this.{method_name}.
Example :
D365FFO / AX – Call an instance method of the same class – X++
If you are inside a class and want to call an instance method that belong to the same class you can call it by using this.{method_name}.
Example :
AX / Dynamics 365 For Finance and Operations blog 