Question

我有一个DynamicObject的子类，我在其中实现了几个隐式运算符（用于自动转换）并覆盖了一些Try [OperationType]方法。

当我尝试使用该类型的对象进行添加（+）操作时，我得到一个异常（问题底部的例外）。

...
var d = GetDynamicObject();
int result = d + 1;
...

我认为这个问题有助于解答is this one。描述的行为是正确的，但我的动态对象定义了几个静态隐式运算符，我认为问题在于字符串1。当我为string定义隐式运算符时，que add（+）操作会抛出异常。我可以通过stacktrace观察到问题可能是他无法绑定运算符，而我开始认为这是因为某种添加/连接混淆。

我简化了我的代码并编写了这个测试，我认为它描绘了这种情况。当我为字符串注释隐式运算符时，eveything效果很好。

我做错了吗？我还需要覆盖一些方法吗？任何想法？

public class Program
{
    static void Main(string[] args)
    {
        try
        {
            var d = GetDynamicObject();
            int result = d + 1;
            Console.WriteLine("OK: " + result);
        }
        catch (Exception)
        {
            Console.WriteLine("Error!");
        }

        Console.ReadLine();
    }

    public static dynamic GetDynamicObject()
    {
        return new MyDynamicObject();
    }
}


public class MyDynamicObject : DynamicObject
{
    public static implicit operator int(MyDynamicObject obj)
    {
        return 0;
    }

    public static implicit operator long(MyDynamicObject obj)
    {
        return 0;
    }

    public static implicit operator double(MyDynamicObject obj)
    {
        return 0;
    }

    // Works when commented
    public static implicit operator string(MyDynamicObject obj)
    {
        return null;
    }

    public override bool TryBinaryOperation(BinaryOperationBinder binder, object arg, out object result)
    {
        Console.WriteLine("MyDynamicObject.TryBinaryOperation");
        return base.TryBinaryOperation(binder, arg, out result);
    }  
}

例外：

Microsoft.CSharp.RuntimeBinder.RuntimeBinderInternalCompilerException was unhandled
  HResult=-2146233088
  Message=An unexpected exception occurred while binding a dynamic operation
  Source=Microsoft.CSharp
  StackTrace:
       at Microsoft.CSharp.RuntimeBinder.Semantics.ExpressionBinder.WhichSimpleConversionIsBetter(PredefinedType pt1, PredefinedType pt2)
       at Microsoft.CSharp.RuntimeBinder.Semantics.ExpressionBinder.WhichTypeIsBetter(PredefinedType pt1, PredefinedType pt2, CType typeGiven)
       at Microsoft.CSharp.RuntimeBinder.Semantics.ExpressionBinder.WhichBofsIsBetter(BinOpFullSig bofs1, BinOpFullSig bofs2, CType type1, CType type2)
       at Microsoft.CSharp.RuntimeBinder.Semantics.ExpressionBinder.FindBestSignatureInList(List`1 binopSignatures, BinOpArgInfo info)
       at Microsoft.CSharp.RuntimeBinder.Semantics.ExpressionBinder.BindStandardBinop(ExpressionKind ek, EXPR arg1, EXPR arg2)
       at Microsoft.CSharp.RuntimeBinder.RuntimeBinder.BindBinaryOperation(CSharpBinaryOperationBinder payload, ArgumentObject[] arguments, Dictionary`2 dictionary)
       at Microsoft.CSharp.RuntimeBinder.RuntimeBinder.DispatchPayload(DynamicMetaObjectBinder payload, ArgumentObject[] arguments, Dictionary`2 dictionary)
       at Microsoft.CSharp.RuntimeBinder.RuntimeBinder.BindCore(DynamicMetaObjectBinder payload, IEnumerable`1 parameters, DynamicMetaObject[] args, DynamicMetaObject& deferredBinding)
       at Microsoft.CSharp.RuntimeBinder.RuntimeBinder.Bind(DynamicMetaObjectBinder payload, IEnumerable`1 parameters, DynamicMetaObject[] args, DynamicMetaObject& deferredBinding)
       at Microsoft.CSharp.RuntimeBinder.BinderHelper.Bind(DynamicMetaObjectBinder action, RuntimeBinder binder, IEnumerable`1 args, IEnumerable`1 arginfos, DynamicMetaObject onBindingError)
       at Microsoft.CSharp.RuntimeBinder.CSharpBinaryOperationBinder.FallbackBinaryOperation(DynamicMetaObject target, DynamicMetaObject arg, DynamicMetaObject errorSuggestion)
       at System.Dynamic.DynamicObject.MetaDynamic.<>c__DisplayClass9_0.<BindBinaryOperation>b__0(DynamicMetaObject e)
       at System.Dynamic.DynamicObject.MetaDynamic.CallMethodWithResult(String methodName, DynamicMetaObjectBinder binder, Expression[] args, Fallback fallback, Fallback fallbackInvoke)
       at System.Dynamic.DynamicObject.MetaDynamic.BindBinaryOperation(BinaryOperationBinder binder, DynamicMetaObject arg)
       at System.Dynamic.BinaryOperationBinder.Bind(DynamicMetaObject target, DynamicMetaObject[] args)
       at System.Dynamic.DynamicMetaObjectBinder.Bind(Object[] args, ReadOnlyCollection`1 parameters, LabelTarget returnLabel)
       at System.Runtime.CompilerServices.CallSiteBinder.BindCore[T](CallSite`1 site, Object[] args)
       at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)
       at WIG.Common.Tests.Program.Main(String[] args) in C:\WIG\WIG Framework\Dev\WIG.Common.Tests\Program.cs:line 74
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

Answer 1

这是a bug in the framework（编辑：Fixed in the corefx codebase，因此.NET Core 2.0.4及更高版本不应该看到此问题）。我们可以看到dynmic没有DynamicObject发生同样的事情：

public class Castable
{
    public static implicit operator int(Castable obj) => 3;

    public static implicit operator string(Castable obj) => "abc";
}

…

dynamic d = new Castable();
var result = d + 2;    // Throws RuntimeBinderInternalCompilerException in NetFX
                       // IndexOutOfRangeException in CoreFX.

将dynamic更改为var并且静态绑定器正在运行而不是动态且（没有此错误）将result设置为5。注释掉转换运算符和动态绑定器可以使用另一个很好。

问题在于处理解析与+一起使用的转换，作为内置运算符用于加法和字符串连接，会导致逐个错误。

如您所知，1 + 2被视为加法，"abc" + x被视为string.Concat("abc", x)。在d + 1 d为dynamic的情况下，活页夹需要确定使用哪个。

在比较可能性时，有些＆＃34;简单＆＃34;目标类型在表中查找。如果可能的话，该目标的枚举值将低于给定值，所以显然首先要做的是查看是否是这种情况。

但遗憾的是，该检查使用<=进行该检查而不是<，但是与之比较的限制是允许的最高限度，因此<是正确的。超出限制的值恰好是string。因此，如果您将动态活页夹置于转换为＆＃34;简单＆＃34;之间的情况下。类型和转换为字符串，它决定它可以比较两种可能性，因为它们都是＆＃34;简单＆＃34;，试图在查找表中找到一个索引超出数组范围的答案。取决于它的版本并使用IndexOutOfRangeException进行爆炸，或者它会触及断言以确保它不会正确地执行它将要执行的操作，并以{{1 }}

在DynamicObject上添加操作

1 个答案: