如何使用非常相似的代码 if/else 语句正确重构这么大的代码？

Question

我正在尝试重构这段代码，它会变得更大，我想知道哪种方法更好。

string obje = String.Empty;
long userId = 0;
long objNewId = 0;
long objOldId = 0;
string action = String.Empty;

if (oldObject.GetType() == typeof(FooDto))
{
    obje = ConstantParams.WCFLOG_APPLICATION_Foo;
    FooDto newFoo = (FooDto)response.Data;
    FooDto oldFoo = (FooDto)oldObject;

    userId = newFoo.UserApplicationId;
    objNewId = newFoo.Id;
    objOldId = oldFoo.Id;
}
else if (oldObject.GetType() == typeof(BarDto))
{
    obje = ConstantParams.WCFLOG_APPLICATION_Bar;
    BarDto newBar = (BarDto)response.Data;
    BarDto oldBar = (BarDto)oldObject;

    userId = newBar.UserApplicationId;
    objNewId = newBar.Id;
    objOldId = oldBar.Id;
}

action = (objOldId == 0) ? ConstantParams.WCFLOG_APPLICATION_NEW : ConstantParams.WCFLOG_APPLICATION_UPD;

string message = Helper.GenerateMessage(action, obje, userId, objNewId);

问题是可能会写这样的东西，但我不知道这样的东西是否可行：

obje = ConstantParams.WCFLOG_APPLICATION_[[XXX]];
[[XXX]]Dto newItem = ([[XXX]]Dto)response.Data;
[[XXX]]Dto oldItem = ([[XXX]]Dto)oldObject;

userId = newItem .UserApplicationId;
objNewId = newItem .Id;
objOldId = oldItem .Id;

Answer 1

假设 Foo、Bar 和它们的对应物都继承自或实现了一个包含 Id 和 UserApplicationId 的公共 class - 我们称它为 SuperclassDto 因为你没有指定，这可以就这么简单：

string obje = String.Empty;
long userId = 0;
long objNewId = 0;
long objOldId = 0;
string action = String.Empty;

obje = ConstantParams.WCFLOG_APPLICATION_Foo;

SuperclassDto newDto = (SuperclassDto)response.Data;
SuperclassDto oldDto = (SuperclassDto)oldObject;

userId = newFoo.UserApplicationId;
objNewId = newDto.Id;
objOldId = oldDto.Id;

action = (objOldId == 0) ? ConstantParams.WCFLOG_APPLICATION_NEW : ConstantParams.WCFLOG_APPLICATION_UPD;

string message = Helper.GenerateMessage(action, obje, userId, objNewId);

如果您的 inheritance/implementation 层次结构不是这么简单，您应该能够强制进入这种状态。

如何使用非常相似的代码 if/else 语句正确重构这么大的代码？

How to correctly refactor this big and with very similar code if/else statements?

c#

refactoring

if-statement