Adding Method Implementations

After defining the metadata of a control, you add the method implementation to the control.

The following restrictions apply with regard to the method names:

Do not use names of methods that are or will be provided by a superclass. Due to inheritance, your implementation would overwrite the implementation of the superclass.
Names starting with set.../get.../insert.../add.../remove.../indexOf.../destroy... shall not be used because they may collide with setters/getters for properties or aggregations you or a superclass defined.
Names starting with attach.../detach.../fire may collide with methods created for events.

The following method names have a specific meaning and should be used accordingly:

on...: Used for event handlers that are automatically bound to browser events
init: Used for the initialization function that is called after control instantiation
renderer: Used for the function that creates the control's HTML

Note

Any method in your inheriting control overrides methods with the same name in the superclass. If, for example, your control implements the init() method, the init() of the superclass will no longer be executed. The control is then no longer properly initialized and this typically causes an error. To avoid breaking the control, call the superclass method.

Consider also that the superclass might implement the method later on, or removes its own method implementation because it is not needed anymore. We recommend that you check for the existence of the superclass method before calling it:

sap.ui.somelib.SomeControl.extend("my.OwnControl", {
       ...
       init: function() {
             if (sap.ui.somelib.SomeControl.prototype.init) { // check whether superclass implements the method
                    sap.ui.somelib.SomeControl.prototype.init.apply(this, arguments); // call the method with the original arguments
             }

             //... do any further initialization of your subclass... 
       }