blocks|key|1458930|text|我在Java中工作，它有相同的API方法，当我读代码的时候，我就是摸不着头脑(因为某些原因)；因此，我总是相反地读它，在你的例子中，"t可赋值给IPlugin“。所以，如果C#有像乔纳森建议的那样"+is”，我总是会使用它--当在Java中反映"instanceof“对类对象不起作用，只对对象的实例起作用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1458931|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I work in Java which has the same API method and I just can't get my mind to grok it when reading the code (for some reason); therefore, I always read it in reverse as, in your case, "t is assignable to IPlugin). So if C# has "is" as Jonathon suggests, I would always use it - when reflecting in Java "instanceof" does not work for Class objects, only instances of the object.

blocks|key|1459002|text|这通常发生在包含当前程序集引用的类型IPlugin的程序集与包含您正在迭代的类型的程序集所引用的程序集之间不匹配时。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1459003|我建议你打印出来：|1459004|typeof+(IPlugin).Module.FullyQualifiedName|code-block|syntax|javascript|1459005|和|1459006|foreach+(var+type+in+t.GetInterfaces+())+
{++++
++++Console.WriteLine+(type.Module.FullyQualifiedName)
}|1459007|看看哪里不匹配。|1459008|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

That typically happens when there's a mismatch between the assembly which contains the type IPlugin that the current assembly references, and the assembly which is referenced by the assembly containg the types you're iterating over.

I suggest you print:

<pre><code>typeof (IPlugin).Module.FullyQualifiedName
</code></pre>

and

<pre><code>foreach (var type in t.GetInterfaces ()) 
{ 
 Console.WriteLine (type.Module.FullyQualifiedName)
}
</code></pre>

To see where the mismatch is.

blocks|key|1459065|text|当应用于测试继承或检测接口实现时，Type.IsAssignableFrom方法的名称是模糊和混乱的。为了实现这些目的，下面的包装器会更有意义：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1459066|++++public+static+bool+CanBeTreatedAsType(this+Type+CurrentType,+Type+TypeToCompareWith)
++++{
++++++++//+Always+return+false+if+either+Type+is+null
++++++++if+(CurrentType+==+null+%7C%7C+TypeToCompareWith+==+null)
++++++++++++return+false;

++++++++//+Return+the+result+of+the+assignability+test
++++++++return+TypeToCompareWith.IsAssignableFrom(CurrentType);
++++}|code-block|syntax|javascript|1459067|然后，人们可以拥有更容易理解的应用程序代码，例如：|1459068|++++bool+CanBeTreatedAs+=+typeof(SimpleChildClass).CanBeTreatedAsType(typeof(SimpleClass));
++++CanBeTreatedAs+=+typeof(SimpleClass).CanBeTreatedAsType(typeof(IDisposable));|1459069|与“is”关键字相比，此方法的优点是可以在运行时使用它来测试未知的任意类型，而“is”关键字(以及泛型类型参数)需要特定类型的编译时知识。|1459070|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

The name of the Type.IsAssignableFrom method is vague and confusing when applied to testing inheritance or detecting interface implementations. The following wrapper for these purposes would make a lot more sense:

<pre><code> public static bool CanBeTreatedAsType(this Type CurrentType, Type TypeToCompareWith)
 {
 // Always return false if either Type is null
 if (CurrentType == null || TypeToCompareWith == null)
 return false;

 // Return the result of the assignability test
 return TypeToCompareWith.IsAssignableFrom(CurrentType);
 }
</code></pre>

Then, one can have more understandable application code such as:

<pre><code> bool CanBeTreatedAs = typeof(SimpleChildClass).CanBeTreatedAsType(typeof(SimpleClass));
 CanBeTreatedAs = typeof(SimpleClass).CanBeTreatedAsType(typeof(IDisposable));
</code></pre>

The advantage of this method instead of the 'is' keyword is that it can be used at run-time to test unknown, arbitrary Types, whereas the 'is' keyword (and a generic Type parameter) requires compile-time knowledge of specific Types.

blocks|key|1674176|text|有时这是动态程序集引用另一个程序集的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1674177|一件简单的事情就是禁用程序集上的本地复制(在visual+studio中，右击引用并将copy+local设置为false)。这样可以更容易地确定程序集所在的目录。|1674178|如果.NET不知道如何初始化类型，你也可以实现一个程序集解析器。|1674179|++++++++AppDomain.CurrentDomain.AssemblyResolve+%2B=+new+ResolveEventHandler([Resolve+Function]);|code-block|syntax|javascript|1674180|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Sometimes it's an issue with the dynamic assembly referencing another assembly.

One simple thing to do it to disable local copy on the assembly (in visual studio right click the reference and set copy local to false). This should make it easier to nail down the directory where the assembly lives.

You can also implement an assembly resolver in-case .NET doesn't know how to initalize the type.

<pre><code> AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler([Resolve Function]);
</code></pre>

I am working on a plugin system that loads .dll's contained in a specified folder. I am then using reflection to load the assemblies, iterate through the types they contain and identify any that implement my <code>IPlugin</code> interface. 

I am checking this with code similar to the following: 

<pre><code>foreach(Type t in myTypes )
{
 if( typeof(IPlugin).IsAssignableFrom(t) )
 {
 ...
 }
}
</code></pre>

For some reason IsAssignableFrom() keeps returning false when it should be returning true. I have tried replacing the <code>t</code> by explicitly giving it a type that should pass, and it works fine, but for some reason it isn't working with the types that are returned from the loaded assembly. To make things stranger, the code works fine on my co-worker's machine but not on mine.

Does anyone know of anything that might cause this sort of behavior?

Thanks

IsAssignableFrom() returns false when it should return true

Java

我正在开发一个插件系统，可以加载包含在指定文件夹中的.dll文件。然后，我使用反射来加载程序集，遍历它们包含的类型，并标识实现我的IPlugin接口的任何类型。我正在使用类似于以下代码的代码检查：foreach(Type t in myTypes ){    if( typeof(IPlugin).IsAssignab...

问IsAssignableFrom()在应该返回true时返回false
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