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如何在fsharp的对象表达式中使用“member val”?

Tomas Jansson · 技术社区 · 7 年前

我在F#中有一个接口(由某个typescript生成),如下所示:

type [<AllowNullLiteral>] AppOptions =
    abstract credential: Admin.Credential.Credential option with get, set
    abstract databaseAuthVariableOverride: Object option with get, set
    abstract databaseURL: string option with get, set
    abstract storageBucket: string option with get, set
    abstract projectId: string option with get, set

我以为创建这种类型的实例的最简单方法是创建一个简单的对象表达式,但是我无法使它工作。不是 member val 在对象表达式中允许吗?如果不是,那么在所有属性上使用getter和setter创建接口的简单实例的最简单方法是什么?这是我尝试过的,但没有成功:

let options = 
    { new Admin.AppOptions with
        member val credential: Admin.Credential.Credential option = None with get, set 
        member val databaseAuthVariableOverride: obj option = None with get, set 
        member val databaseURL: string option = None with get, set 
        member val databaseURL: string option = None with get, set 
        member val projectId: string option = None with get, set 
    }

1 回复 | 直到 7 年前

7sharp9 7 年前

我认为成员var不在对象表达式规范中,只允许使用这样的长表单属性:

let options =
    let mutable credential = None 
    let mutable databaseAuthVariableOverride = None
    let mutable databaseURL = None
    let mutable storageBucket = None
    let mutable projectId = None
    { new AppOptions with
        member x.credential with get() = credential and set v = credential <- v
        member x.databaseAuthVariableOverride with get() = databaseAuthVariableOverride and set v = databaseAuthVariableOverride <- v
        member x.databaseURL with get() = databaseURL and set v = databaseURL <- v
        member x.storageBucket with get() = storageBucket and set v = storageBucket <- v
        member x.projectId with get() = projectId and set v = projectId <- v
    }

编译器会像这样投射C类代码:

[assembly: FSharpInterfaceDataVersion(2, 0, 0)]
[assembly: AssemblyVersion("0.0.0.0")]
[CompilationMapping(SourceConstructFlags.Module)]
public static class _
{
    [Serializable]
    [AllowNullLiteral]
    [CompilationMapping(SourceConstructFlags.ObjectType)]
    public interface AppOptions
    {
        override FSharpOption<object> credential
        {
            get;
            set;
        }

        override FSharpOption<object> databaseAuthVariableOverride
        {
            get;
            set;
        }

        override FSharpOption<string> databaseURL
        {
            get;
            set;
        }

        override FSharpOption<string> storageBucket
        {
            get;
            set;
        }

        override FSharpOption<string> projectId
        {
            get;
            set;
        }
    }

See sharplab

正常类型在这里可能更简洁:

    type t() = 
     interface AppOptions with
         member val credential = None with get, set
         member val databaseAuthVariableOverride = None with get, set 
         member val databaseURL = None with get, set 
         member val storageBucket = None with get, set 
         member val projectId = None with get, set