Hi, 
in depends api, we add fields that will trigger the function. Imagine you have a list of fields to include in depends. 
you can easily put them in a function and call it inside of api.depends. 
Ex: 

    def _get_dependencies(self):
        return ['Field1', 'Field1.Field2', 'Field1.Field3', 'Field3',
                'Field4', 'Field4.Field1', 'Field5','Field6','Field7','Field8','Field9','Field9.Field2','Field9.Field6']

and then : 

@api.multi
@api.depends(_get_dependencies)
def _compute_my_field(self):    //....

That is to say, with a function, you return the fields that you need, to trigger the depends function. 

my case : 
based on the connected user's profile, some fields should trigger the compute function.