在F#中使用哪个，抽象类或接口? [英] Which to use , abstract class or interface in F#?

问题描述

曾经骗人的F#来自C#背景.

Been grokking F# coming from a C# background.

在C#中，决定何时使用接口和何时使用抽象类有明显的区别.在F#中，我看到两者几乎融为一体.我了解到，就CLR而言，在F#中已经完成了与c#相同的操作，但是在使用F#进行编程时最佳实践"是什么?

In C# there is a clear difference in deciding when to use interfaces and when to use abstract classes. In F# I see the two blurring almost into one. I understand under the hood that the same is being done in F# as c# as far as the CLR is concerned, but what is the "best practise" when programming in F# to use?

我应该完全避免类继承吗?

Should I avoid class inheritance altogether?

推荐答案

我认为接口的使用往往比抽象类(与C#这样的面向对象的语言相比)要频繁得多.

I think that interfaces tend to be used much more frequently than abstract classes (compared to object-oriented languages like C#).

在很多情况下，您不需要两者中的任何一个，因为您可以编写更高阶的函数(将函数作为参数，而不是将接口作为参数).但是，有时您可能有两个总是一起使用的功能-在这种情况下，您可以将两个功能分组到一个接口中:

In many cases, you don't need any of the two, because you can just write higher-order function (that takes a function as an argument, instead of taking an interface as an argument). However, sometimes you may have two functions that are always used together - in that case, you can group two functions into an interface:

// Instead of using higher-order function
val foo : (int -> string) -> (string -> int) -> ...

// ..we can define an interface
type TwoWayConversion = 
  abstract ToString : int -> string
  abstract FromString : string -> int

val foo : TwoWayConversion -> ...

我认为这是非常有用的F#编程模式，它以完美的功能样式使用接口.

I think that this is quite useful F# programming pattern that uses interfaces in a perfectly functional style.

另一方面，我仅在编写应该从C#使用的面向对象代码(例如，实现F#抽象类的C#代码)时才使用抽象类-因为从C#的角度来看，这是自然的可扩展性点看法.但是，我认为惯用的F#代码使用的扩展点与C#不同(例如，以函数/接口作为参数)，因此您实际上并不需要抽象类.

On the other hand, I would use abstract classes only when writing object-oriented code that is supposed to be used from C# (e.g. C# code implementing your F# abstract class) - because that's a natural extensibility point from the C# point of view. However, I think that idiomatic F# code uses different extensibility points than C# (e.g. taking function/interface as an argument), so you don't really need abstract classes.

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