好了，你可以这样做：

Delegate method;

...
if (choice == "D") // Consider using a switch...
{
    method = (Func<double>) D;
}

然后的DoSomething 会被宣布为刚代表，这还不是特别好的。

Then DoSomething would be declared as just Delegate, which isn't terribly nice.

另外，也可以来包装方法刚刚进行任何转换的委托要求得到返回值对象：

Another alternative would be to wrap the method in a delegate which just performs whatever conversion is required to get the return value as object:

Func<object> method;


...
if (choice == "D") // Consider using a switch...
{
    method = BuildMethod(D);
}

...

// Wrap an existing delegate in another one
static Func<object> BuildMethod<T>(Func<T> func)
{
    return () => func();
}