F#记录成员评估

本文介绍了F#记录成员评估的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

为什么每次通话都会评估t.b?并且有什么方法可以使它只评估一次?

Why is t.b evaluated on every call? And is there any way how to make it evaluate only once?

type test = { a: float } member x.b = printfn "oh no" x.a * 2. let t = { a = 1. } t.b t.b

推荐答案

这是一个属性；您基本上是在呼叫get_b()成员.

It's a property; you're basically calling the get_b() member.

如果您希望效果在构造函数中发生一次，则可以使用一个类:

If you want the effect to happen once with the constructor, you could use a class:

type Test(a:float) = // constructor let b = // compute it once, store it in a field in the class printfn "oh no" a * 2. // properties member this.A = a member this.B = b