[英]Unable to cast generic type to interface
I have those types: 我有那些类型:
public interface ICommand {}
public class RemoveCommand<T>: ICommand
{
public int Id {get; set;}
}
public interface ICommandHandler<TCommand> where TCommand: ICommand
{
void HandleCommand(TCommand command);
}
public class RemoveCommandHandler<T> : ICommandHandler<RemoveCommand<T>>
{
public void HandleCommand(SoftRemoveCommand<T> command)
{
...
}
}
While I was trying to resolve my ICommandHandler using Castle Windsor I received a cast exceptions. 当我尝试使用Castle Windsor解析ICommandHandler时,我收到了强制转换异常。 So I wrote this: 所以我这样写:
var obj = new RemoveCommandHandler<RemoveCommand<MyClass>>();
bool t1 = obj is ICommandHandler<RemoveCommand<MyClass>>; //return false!
bool t2 = obj.GetType().IsAssignableFrom(ICommandHandler<RemoveCommand<MyClass>>); //also false!
So my question is: Why my RemoveCommandHandler is not assignable from ICommandHandler? 所以我的问题是:为什么不能从ICommandHandler分配我的RemoveCommandHandler?
Your generic class declaration is RemoveCommandHandler<T>
. 您的通用类声明是RemoveCommandHandler<T>
。 So If you have class RemoveCommandHandler<RemoveCommand<MyClass>>
, this means that your T
is RemoveCommand<MyClass>
. 因此,如果您具有类RemoveCommandHandler<RemoveCommand<MyClass>>
,则意味着您的T
是RemoveCommand<MyClass>
。
So you should change RemoveCommandHandler<RemoveCommand<MyClass>>
to RemoveCommandHandler<MyClass>
and the code should work: 因此,您应该将RemoveCommandHandler<RemoveCommand<MyClass>>
更改为RemoveCommandHandler<MyClass>
,并且代码应该可以工作:
var obj = new RemoveCommandHandler<MyClass>();
bool t1 = obj is ICommandHandler<RemoveCommand<MyClass>>; // returns true
Although for second check you need to switch sides: 尽管需要进行第二次检查,但还是要换面:
bool t2 = typeof(ICommandHandler<RemoveCommand<MyClass>>).IsAssignableFrom(obj.GetType()); // returns true
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