添加构造函数以deftype创建的类 [英] Add constructor to deftype created class

问题描述

为了与Java的互操作性，我需要一个具有执行初始化的nullary构造函数的类。
这个类的对象需要有类似于可变的java字段的东西（即，对象表示游戏的后端，并且需要保持游戏状态）。

For the purposes of interoperability with Java, I need a class that has a nullary constructor that performs initialization. Objects of this class need to have something resembling mutable java fields (namely, the object represents the backend of a game, and needs to keep game state).

deftype 我想做 除非提供一个nullary构造函数（因为我创建了一个包含字段的类）。

deftype does everything I want to do except provide a nullary constructor (since I'm creating a class with fields).

我不需要字段是公共可读的，所以我可以想到4个解决方案：

I don't need the fields to be publicly readable, so I can think of 4 solutions:

使用gen-我不想这样做，如果我可以避免它。

不知何故编码私人成员变量的知识deftype;我已经被告知这不能做。

编写一个修改的deftype，也创建一个nullary构造函数;坦白说，我不知道Clojure足够这样。

接受由deftype创建的类，并以某种方式添加一个新的构造函数。

Use gen-class; I don't want to do this if I can avoid it.
Somehow encoding private member variables outside of the knowledge of deftype; I've been told this can't be done.
Writing a modified deftype that also creates a nullary constructor; frankly I don't know clojure well enough for this.
Taking the class created by deftype and somehow adding a new constructor to it.

最后，我需要一个Java类，因为我将把它交给Java代码，将从类中创建一个新的对象。

At the end of this, I need to have a Java class, since I will be handing it off to Java code that will be making a new object from the class.

Are任何我建议的解决方案（或任何我没有想过）除了使用gen类可行吗？

Are any of the solutions I suggested (or any that I haven't thought of) other than using gen-class viable?

推荐答案

如果你的Java互操作要求是同时具体和不可动摇的，那么在适当的时候，写一个Java短语是绝对没有可耻的。你可以用一个单独的静态工厂方法写一个Java类，返回一个 deftype 类的实例，并且做任何你需要的初始化/设置。

There's absolutely no shame in, where appropriate, writing a dash of Java if your Java interop requirements are simultaneously specific and unshakable. You could write a Java class with a single static factory method that returns an instance of the deftype class and that does whatever initialization/setup you need.

或者，你可以在Clojure中写一个nullary工厂函数，并直接从Java中调用它。

Alternatively, you can write a nullary factory function in Clojure, and call that directly from Java all day long.

在任何情况下， deftype 或 defrecord 旨在是（或将是）全功能的互操作设施。 gen-class 肯定是最接近的，这就是为什么它被推荐。

In any case, neither deftype nor defrecord are intended to be (or will they ever be) fully-featured interop facilities. gen-class certainly comes the closest, which is why it's been recommended.

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