使用Ninject绑定到常量和绑定到范围中的类型的用法 [英] Usage of binding to constants and binding to types in scopes with Ninject

问题描述

哪种方式创建单个对象到接口的绑定是首选，何时以及为什么:

Which way of creating bindings of single object to interface is preferable, when and why:

Kernel.Bind<IFoo>().ToConstant(new Foo());

或

Kernel.Bind<IFoo>().To(typeof(Foo)).InSingletonScope();

或者，如果两种方法都不正确并且最好避免，应该使用什么替代方法?

Or, if both ways are incorrect and better to be avoided, what should be used instead?

推荐答案

使用这两种构造，您可以完成相同的工作.但是，在后一种方法中，将单个Foo对象的构造推迟到第一次Get调用之前. 让我用一个小例子来说明这一点.考虑以下应用程序:

With both constructions you accomplish the same. However, in the latter approach construction of the single Foo object is deferred until the first Get call. Let me illustrate that with a little example. Consider the following application:

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting the app");

        IKernel kernel = new StandardKernel();
        kernel.Bind<IFoo>().ToConstant(new Foo());

        Console.WriteLine("Binding complete");

        kernel.Get<IFoo>();

        Console.WriteLine("Stopping the app");
    }
}

public interface IFoo
{
}

public class Foo : IFoo
{
    public Foo()
    {
        Console.WriteLine("Foo constructor called");
    }
}

这将为您提供输出:

Starting the app
Foo constructor called
Binding complete
Stopping the app

现在，让我们将ToConstant调用替换为To(typeof(Foo)).InSingletonScope()

Now, let's replace the ToConstant call with To(typeof(Foo)).InSingletonScope()

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting the app");

        IKernel kernel = new StandardKernel();
        kernel.Bind<IFoo>().To(typeof(Foo)).InSingletonScope();

        Console.WriteLine("Binding complete");

        kernel.Get<IFoo>();

        Console.WriteLine("Stopping the app");
    }
}

public interface IFoo
{
}

public class Foo : IFoo
{
    public Foo()
    {
        Console.WriteLine("Foo constructor called");
    }
}

现在的输出是:

Starting the app
Binding complete
Foo constructor called
Stopping the app

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