Question

我最近遇到了ASP.net vnext的AssemblyNeutral属性。

如果我必须具体，那么您将在Logging资源库中找到该属性用法。 https://github.com/aspnet/logging

还有许多其他存储库，但这很简单。

现在根据许多博客，如果我们使用AssemblyNeutral属性，那么该接口或类型不与程序集绑定，因此我们可以在其他需要相同合同的框架中使用AssemblyNeutral属性定义相同的接口。

所以创建示例我在ASP.net vnext类库项目中创建了自己的小型记录器库但它给了我类型转换错误。

 namespace MyLogger
{
    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILogger
    {      
        void Write(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter);
        bool IsEnabled(LogLevel logLevel);
        IDisposable BeginScope(object state);
    }

    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILoggerFactory
    {       
        ILogger Create(string name);
        void AddProvider(ILoggerProvider provider);
    }
    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILoggerProvider
    {        
        ILogger Create(string name);
    }

    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public enum LogLevel
    {
        Verbose = 1,
        Information = 2,
        Warning = 3,
        Error = 4,
        Critical = 5,
    }

    public class MyLogger : ILogger
    {
        public IDisposable BeginScope(object state)
        {
            return null;  
        }

        public bool IsEnabled(LogLevel logLevel)
        {
            return true;
        }

        public void Write(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
        {
            System.IO.File.AppendAllText("C:\\Testlog.txt", "This is test log" + System.Environment.NewLine);
        }
    }

    public class MyLoggerProvider : ILoggerProvider
    {
        private readonly Func<string, LogLevel, bool> _filter;

        public MyLoggerProvider(Func<string, LogLevel, bool> filter)
        {
            _filter = filter;
        }

        public ILogger Create(string name)
        {
            return new MyLogger();
        }       
    }

    public static class MyLoggerExtentions
    {
        public static ILoggerFactory AddMyLogger(this ILoggerFactory factory, Func<string, LogLevel, bool> filter)
        {
            factory.AddProvider(new MyLoggerProvider(filter));
            return factory;
        }
    }
}

现在我尝试在SampleApp（Logging Repository SampleApp）中使用。你可以看到它给了我Cast Error。为什么这样？

enter image description here

Answer 1

IDE尚未正确处理源中定义的程序集中性接口。这就是你看到错误的原因。

Answer 2

我部分同意Visual Studio 2015 Preview IDE不支持AssemlbyNeutral属性，但问题出在其他地方。

实际上，当我们在自定义程序集中再次定义Interface或Type时，如果我们希望它支持AssemblyNeutral，那么它必须具有与原始接口相同的名称空间。

在我的示例中，我通过将接口放入New Namespace来做错了。

我已更新代码，然后我在Visual Studio 2015中构建预览它编译甚至正确执行。

所以要记住的主要事情是＆＃34;将程序集中性接口和类型放在原始程序集所在的相同名称空间中，并且＃34;。

以下是更新的代码。

namespace Microsoft.Framework.Logging
{
    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILogger
    {
        void Write(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter);
        bool IsEnabled(LogLevel logLevel);
        IDisposable BeginScope(object state);
    }

    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILoggerFactory
    {
        ILogger Create(string name);
        void AddProvider(ILoggerProvider provider);
    }

    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public interface ILoggerProvider
    {
        ILogger Create(string name);
    }

    #if ASPNET50 || ASPNETCORE50
    [Microsoft.Framework.Runtime.AssemblyNeutral]
    #endif
    public enum LogLevel
    {
        Verbose = 1,
        Information = 2,
        Warning = 3,
        Error = 4,
        Critical = 5,
    }
}

namespace MyLogger
{


    public class MyLogger : ILogger
    {
        public IDisposable BeginScope(object state)
        {
            return null;
        }

        public bool IsEnabled(LogLevel logLevel)
        {
            return true;
        }

        public void Write(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
        {
            System.IO.File.AppendAllText("C:\\Testlog.txt", "This is test log" + System.Environment.NewLine);
        }
    }

    public class MyLoggerProvider : ILoggerProvider
    {
        private readonly Func<string, LogLevel, bool> _filter;

        public MyLoggerProvider(Func<string, LogLevel, bool> filter)
        {
            _filter = filter;
        }

        public ILogger Create(string name)
        {
            return new MyLogger();
        }
    }

    public static class MyLoggerExtentions
    {
        public static ILoggerFactory AddMyLogger(this ILoggerFactory factory, Func<string, LogLevel, bool> filter)
        {
            factory.AddProvider(new MyLoggerProvider(filter));
            return factory;
        }
    }
}

ASp.net vnext中的AssemblyNeutral属性

2 个答案: