f#NativePtr.stackalloc在Struct构造函数中 [英] f# NativePtr.stackalloc in Struct Constructor

问题描述

我正在做一些F#性能测试，并试图在堆栈上而不是堆上创建一个数组(值与引用类型).我正在使用NativePtr.stackalloc在堆栈上分配内存.在下面的第一个构造函数中出现错误.

type StackArray<'T when 'T : unmanaged> =
    struct
        val pointer: nativeptr<'T>

        new(x) = { pointer = NativePtr.stackalloc x}
        new(pointer) = { pointer = pointer}
    end    

// This give a System.TypeInitializationException with internal System.InvalidProgramException   
let ints2 = new StackArray<int>(10) 

// This works fine
let (pointer:nativeptr<int>) = NativePtr.stackalloc 10
let ints = new StackArray<int>(pointer) 

我可以在函数中简单地使用第二种方法，但这真的使我感到困惑，为什么我不能在构造函数中分配内存.

解决方案

如果在函数中使用stackalloc进行分配，则返回后，必须释放分配的堆栈空间(否则就不会有堆栈)

我原以为该错误稍后会在使用该对象时发生，但立即出现错误并不完全令人惊讶

I'm doing some F# performance testing and am trying to create an array on the stack rather then the heap (value vs reference type). I am using NativePtr.stackalloc to allocate memory on the stack. Getting an error in the first constructor below.

type StackArray<'T when 'T : unmanaged> =
    struct
        val pointer: nativeptr<'T>

        new(x) = { pointer = NativePtr.stackalloc x}
        new(pointer) = { pointer = pointer}
    end    

// This give a System.TypeInitializationException with internal System.InvalidProgramException   
let ints2 = new StackArray<int>(10) 

// This works fine
let (pointer:nativeptr<int>) = NativePtr.stackalloc 10
let ints = new StackArray<int>(pointer) 

I could simply use the second method in a function, but It's really bugging me why I can't allocate the memory inside the constructor.

解决方案

If you allocate using stackalloc in a function, once you have returned, the stack space allocated must be freed (or you wouldn't have a stack)

I would have expected the error to have occured later, when the object was used, but an error immediately isn't completely surprising

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