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从C调用F函数并获取空引用异常

fastfunc closures f# c#

dan · 技术社区 · 15 年前

我正在使用安装了2009年10月f CTP的Visual Studio 2008。

我想从我的C程序中调用一些F代码。大多数类型的f函数似乎都可以工作,但有些函数在f中没有初始化,并且正在抛出NullReferenceExceptions。执行此操作的是闭包和部分应用的函数,即在C中显示为fastfunc<>类型的内容。

是否有我做错或忘记的事情,或者这可能是F或.NET的错误?

下面的代码是为了演示这个问题。我并没有在实际的应用程序中使用这段代码。 而且,在f内,一切都正常工作。这是一个从F到C的问题

namespace FS      
module FunctionTypes =

    //these all work in c# as expected
    let Value = "value"

    let OneParam (str:string) = str

    let TwoParam (str:string) (str2:string) = str + " " + str2

    let Lambda =
        fun () -> "lambda"  


    //these functions are null references in C#
    // they do work as expected in F# interactive mode
    let PartialApplication = TwoParam "what's up"

    let Closure = 
        let o = new System.Object()
        fun (i:int) -> o.ToString() + i.ToString()

    let ClosureWrapper (i:int) =
        Closure i

C(参考F项目和fsharp.core)

 //these work as expected:
        var oneParam = FS.FunctionTypes.OneParam("hey");
        var twoParam = FS.FunctionTypes.TwoParam("yeah", "you");
        var lambdaFunction = FS.FunctionTypes.Lambda();
        var value = FS.FunctionTypes.Value;
        //  in the May09 CTP, Value returned null, 
        //      so it must have been fixed in Oct09 CTP



 //these do not work--each throws a NullReferenceException.
        var partial = FS.FunctionTypes.PartialApplication.Invoke("hello");
        var closure = FS.FunctionTypes.Closure.Invoke(1);
        var closureWrapper = FS.FunctionTypes.ClosureWrapper(1);

 //  FS.FunctionTypes.Closure itself is null, 
 //  so is FS.FunctionTypes.PartialAppliction.
 //  FS.FunctionTypes.ClosureWrapper is a regular function, 
 //    but it calls Closure, which is null