TypeScript 中的抽象构造函数类型
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Abstract constructor type in TypeScript
提问by John Weisz
The type signature for a non-abstract class (non-abstract constructor function) in TypeScript is the following:
TypeScript 中非抽象类（非抽象构造函数）的类型签名如下：
declare type ConstructorFunction = new (...args: any[]) => any;
This is also called a newabletype. However, I need a type signature for an abstractclass (abstract constructor function). I understand it can be defined as having the type Function, but that is waytoo broad. Isn't there a more precise alternative?
这也称为可新类型。但是，我需要一个抽象类（抽象构造函数）的类型签名。我的理解是可以被定义为具有类型Function，但就是这样过于宽泛。没有更精确的选择吗？
Edit:
编辑：
To clarify what I mean, the following little snippet demonstrates the difference between an abstract constructor and a non-abstract constructor:
为了澄清我的意思，以下小片段演示了抽象构造函数和非抽象构造函数之间的区别：
declare type ConstructorFunction = new (...args: any[]) => any;
abstract class Utilities {
...
}
var UtilityClass: ConstructorFunction = Utilities; // Error.
Type 'typeof Utilities' is not assignable to type 'new (...args: any[]) => any'.
Cannot assign an abstract constructor type to a non-abstract constructor type.
类型“typeof Utilities”不可分配给类型“new (...args: any[]) => any”。
不能将抽象构造函数类型分配给非抽象构造函数类型。
回答by Tehau Cave
Was just struggling with a similar problem myself, and this seems to work for me:
我自己只是在为类似的问题而苦苦挣扎，这似乎对我有用：
type Constructor<T> = Function & { prototype: T }
回答by gaperton
Having the same problem. I guess, an essence of abstract class constructor signature is an absenseof new ( ... ) : Xthingy in its declaration. That's why it can be declared explicitly.
有同样的问题。我想，抽象类的构造函数签名的实质是由于缺少的new ( ... ) : X啄在其声明。这就是为什么可以显式声明它的原因。
However. You can do this, and it will compile.
然而。你可以这样做，它会编译。
var UtilityClass: typeof Utilities = Utilities;
typeof Somethingis a nice way to reference constructor types, however, it cannot be extended.
typeof Something是一种引用构造函数类型的好方法，但是它不能被扩展。
And in any case you can do thing like this:
在任何情况下，您都可以这样做：
var UtilityClass: ConstructorFunction = <any> Utilities;
回答by Nitzan Tomer
The whole point with abstract classes (in OO in general) is that you can not instantiate them, you need a concrete non-abstract implementation.
抽象类（通常在 OO 中）的全部意义在于您无法实例化它们，您需要一个具体的非抽象实现。
I assume that you want to have different implementations to that abstract class and want to be able to receive one of those implementations (as a parameter or something of the likes).
If that's the case, then maybe this might solve your problem:
我假设您希望对该抽象类有不同的实现，并希望能够接收其中一个实现（作为参数或类似的东西）。
如果是这种情况，那么也许这可以解决您的问题：
declare type ConstructorFunction<T extends Utilities> = new (...args: any[]) => T;
abstract class Utilities { }
class MyUtilities extends Utilities { }
var UtilityClass: ConstructorFunction<MyUtilities> = MyUtilities;
