代碼實現爲班圖

Question

更新3

什麼跡象（單線，鑽石與明星和箭頭）在圖形下方的意思是（從Eric的DDD書P195）：

任何代碼示例來說明，將不勝感激。

Answer 1

金剛石是組合物（也稱爲聚集），或一個has-a關係。箭頭是繼承關係，或者是is-a關係。該行是一個協會。這導致了一個問題：組合和協會有什麼區別。答案是組成更強，通常擁有另一個對象。如果主對象被銷燬，它也將銷燬其組成對象，但不會銷燬它的關聯對象。

在你的榜樣，設施包含（具有-A）LoanInvestment和LoanInvestment繼承的（是-A）投資

這裏是class diagrams using UML一個很好的說明。

這裏是C++中的代碼示例，我不知道C＃的不夠好，和Id可能搞砸了:)

class Facility 
{ 
public: 
    Facility() : loan_(NULL) {} 

    // Association, weaker than Composition, wont be destroyed with this class 
    void setLoan(Loan *loan) { loan_ = loan; } 

private: 
    // Composition, owned by this class and will be destroyed with this class 
    // Defined like this, its a 1 to 1 relationship 
    LoanInvestment loanInvestment_; 
    // OR 
    // One of the following 2 definitions for a multiplicity relation 
    // The list is simpler, whereas the map would allow faster searches 
    //std::list<LoanInvestment> loanInvList_; 
    //std::map<LoanInvestment> loanInvMap_; 

    Loan *loan_: 
    // define attributes here: limit 
}; 

class Loan 
{ 
public: 
    // define attributes here: amount 
    // define methods here: increase(), decrease() 
private: 
    // 1 to 1 relationship, could consider multiplicity with a list or map 
    LoanInvestment loanInvestment_; 
}; 

class Investment 
{ 
    // define attributes here: investor, percentage 
}; 

class LoanInvestment : public LoanInvestment 
{ 
    // define attributes here 
};