Responsibility division by pre and postconditions

Contracts and Assertions - slide 13 : 32

Preconditions and postconditions can be used to divide the responsibility between classes in an object-oriented program

Fulfillment of the precondition
- The responsibility of the caller
- The responsibility of the client in an object-oriented program
Fulfillment of the postcondition
- The responsibility of the called operation
- The responsibility of the server in an object-oriented program

Blame the caller if a precondition of an operation fails

Blame the called operation if the postcondition of an operation fails