当谈到典型的构造函数依赖注入时,我很难理解看似明显的模式问题/限制.例如,假设我有一个ASP.NET MVC3控制器,它看起来像:
Public Class MyController
Inherits Controller
Private ReadOnly mServiceA As IServiceA
Private ReadOnly mServiceB As IServiceB
Private ReadOnly mServiceC As IServiceC
Public Sub New(serviceA As IServiceA, serviceB As IServiceB, serviceC As IServiceC)
Me.mServiceA = serviceA
Me.mServiceB = serviceB
Me.mServiceC = serviceC
End Sub
Public Function ActionA() As ActionResult
' Do something with Me.mServiceA and Me.mServiceB
End Function
Public Function ActionB() As ActionResult
' Do something with Me.mServiceB and Me.mServiceC
End Function
End Class
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我遇到困难的事情是,在任何给定时间,DI容器被要求实例化所有三个依赖项,这个控制器上的操作方法可能只需要一部分依赖项.
似乎假设对象构造是肮脏的,并且没有来自对象构造的副作用或者所有依赖性都被一致地利用.如果物体结构没有吱吱声或有副作用怎么办?例如,如果构建 …
language-agnostic design-patterns dependency-injection asp.net-mvc-3