8.2.1.1 Exercise contracts | COMP.CS.140 Ohjelmointi 3: Rajapinnat ja tekniikat

Question 1 4 points

In design by contract

the services of the interface are defined as a contract where own obligations are created for the caller and the implementor

it is the responsibility of the implementor to check that the service has been called correctly

it is the caller’s responsibility to think what the interface promises to do

a subclass can implement a stronger contract than that of the baseclass

it is the caller’s responsibility how the interface can be called

it is the implementor’s responsibility that the service called according to the contract is provided

Question 2 2 points

Precondition

does not affect the caller

is always checked in the implementation

defines what things must hold when the service is of the interface is called

Question 3 2 points

Postcondition

does not affect the implementor

can be left unfullfilled without the caller noticing

defines what things must hold holds once the execution of the service of the interface has ended

Question 4 2 points

Class invariant

holds for objects of the class always during the execution

is meaningful to the caller of the object’s methods

holds for the objects of the class always before and after method calls