通用方法问题... [英] generic method question...............

问题描述

我目前正在尝试实现通用方法:

I am currently trying to implement a generic method:

public int Save<T>(DomainObject model) where T : BaseConfig
{
...
}

T是实现BaseConfig的一种类型.我需要能够在Save方法中实例化一个通过类型T的新类.

BaseConfig类在实例化时填充其自己的配置值.

因此，在通用的Save方法中，我需要说一些类似的内容:T config = new T()

我很确定上面提供的实例化代码不是正确的实现方式，但是我认为这很好地说明了我要实现的目标.

因此，您可以建议实现此设计的最佳方法吗?

T is a type of class that implements BaseConfig. I need to be able to instantiate a new class of the passed type T in the Save method.

The BaseConfig class populates it''s own config values upon instantiation.

So within the generic Save method I need to say something like: T config = new T()

I''m pretty sure that the instantiation code that I provided above is not the correct way to do it but I think it''s a pretty good illustration of what I''m trying to achieve.

So can you advise on the best way to implement this design?

推荐答案

这不是使用泛型的好方法.在您的示例中，在类实现中未使用T，但这是关键.如果操作正确，则不需要键入case.

有很多设计方法可以达到目的.在某些情况下，您需要将OOP与泛型结合使用.一些想法:

您还可以在DomainObject中使用通用方法，然后使用T类型实例化这些方法.

作为上述方法的一种变体，您可以使整个DomainObject类通用，并使用T对其进行实例化.
您可以将接口IConfig而不是BaseConfig设置为DomainObject已知. DomainObject的实例化将仅定义IConfig的实现； DomainObject仅与接口一起使用，但与在通用实例化时定义的接口实现方式无关.

如果我可以了解有关您的应用程序和预期设计的更多信息，我会建议其他事项，但是您需要显示一些基本方法并解释它们应该做什么. (算法优先！")

—SA

It is not a good way of using generic. In your sample there is not use of T in the class implementation, but this is a key. If you do it correctly, type case is not needed.

There are many design way to achieve the results. In some cases you need to combine OOP with generics. Some ideas:

You can also have generic methods in DomainObject, then you will instantiate those methods with T type.

As a variant of the above you can make whole DomainObject class generic and instantiate it with T.

You can make an interface IConfig instead of BaseConfig and make it known to DomainObject. Instantiation of DomainObject will define only the implementation of IConfig; DomainObject will work with interface only but agnostic about its implementation defined at the moment of generic instantiation.

If I could learn more about your application and intended design, I would advise something else, but you need to show some essential methods and explain what they are supposed to do. ("Algorithms first!")

—SA

只是将new()约束添加到方法中，以指定该类具有无参数的构造函数.没有它，编译器错误是无法创建变量类型"T"的实例，因为它没有new()约束".

Hi,
Just to add the new() constraint to the method to specify that the class has a parameterless constructor . Without it the compiler error is "Cannot create an instance of the variable type ''T'' because it does not have the new() constraint".

public int Save<T>(DomainObject model) where T : BaseConfig, new() {
  T config = new T();
  return 0;
}

艾伦.

我是否正确理解了这个问题?

Alan.

have I understood the question correctly?

这将在您的方法中起作用吗?

Will this work inside your method?

T realType = model as T;

编辑==========

我将"obj"更改为"model".

EDIT ==========

I changed "obj" to "model".

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