public abstract ContractManager getContractManager() must return an instance of a ContractManager implementing the correct contract checking.
public abstract ContractManager getContractManager()必须返回实现了正确的契约检查的 ContractManager的一个实例。
2
The next important feature to take advantage of when migrating from PHP V4 to V5 is support for contract programming through interfaces and abstract classes and methods.
从PHP V 4迁移到PHP v5时要利用的下一个重要特性是支持通过接口、抽象类和方法进行契约编程。
3
The AbstractContract aspect presents two abstract methods that must be overridden when you implement a concrete contract-checker aspect