Replace Nested Conditional with Guard Clauses（以卫语句取代嵌套条件式）

动机（Motivation）

使用卫语句（guard clauses）表现所有特殊情况。

示例

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public double GetPayAmount() {     double result;     if (IsDead)         result = DeadAmount();     else     {         if (IsSeparated)             result = SeparatedAmount();         else         {             if (IsRetired)                 result = RetiredPayAmount();             else                 result = NormalPayAmount();         }     }     return result; }

改为

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public double GetPayAmount() {     if (IsDead)         return DeadAmount();     if (IsSeparated)         return SeparatedAmount();     if (IsRetired)         return RetiredPayAmount();     return NormalPayAmount(); }