每次访问时 F# 静态成员都会更改

Question

这是一个非常简单的 class 和静态属性:

[<AbstractClass; Sealed>]
type test () = 
    static member ttc = (new Random()).Next()

当我访问 ttc 时，它总是发生变化...像这样：（在 fsi.exe）

我的目的是在静态成员中存储值：

type typDimTablesArray () = 
static member DimApplication        = typDimTables.DimApplication      |> Seq.toArray
static member DimApplicationState   = typDimTables.DimApplicationState |> Seq.toArray
static member DimDatetime           = typDimTables.DimDatetime         |> Seq.toArray
static member DimDbQuery            = typDimTables.DimDbQuery          |> Seq.toArray
static member DimDeveloper          = typDimTables.DimDeveloper        |> Seq.toArray
static member DimPlatform           = typDimTables.DimPlatform         |> Seq.toArray

但是我每次访问typDimTablesArray.DimDatetime.Length 它只是再次查询数据库，从不将数据存储在静态成员中...

Answer 1

以下是差异的简短示例：

type Test3() =
    let random = new System.Random()
    let y = random.Next()
    member __.X = random.Next()
    member __.Y = y
    static member val Z = (new Random()).Next()

let x = Test3()

x.X 
x.X
x.Y
x.Y
Test3.Z
Test3.Z

此外，您可以只创建您的类型的实例并传入您需要处理的任何对象。现在，如果它很懒，你可能需要缓存它：

let rnd = new System.Random()
let rnds = Seq.init 10 (fun _ -> rnd.Next())

type Test4(rndsX:int seq) =
    let xx = rndsX |> Seq.cache
    member __.Length = xx |> Seq.toArray |> Seq.length
    member __.First = xx |> Seq.head
    member __.Last = xx |> Seq.last

每次访问时 F# 静态成员都会更改

F# static member changes each time when accessed

f#

f#-interactive