Ways of keeping configuration code out of logic code using Dependency Injection

Question

How can keep all the configuration file code out of my logic code using Settings (ApplicationSettingsBase) and Dependency Injection?

With configuration I mean a cust

Answer 1

In my applications I do what you have done above with IoC. That is to say, having my IoC container (StructureMap also) inject an IApplicationSettings into my classes.

For example, in an ASP.NET MVC3 project it may look like:

Public Class MyController
    Inherits Controller

    ...
    Private ReadOnly mApplicationSettings As IApplicationSettings

    Public Sub New(..., applicationSettings As IApplicationSettings)
        ...
        Me.mApplicationSettings = applicationSettings
    End Sub

    Public Function SomeAction(custId As Guid) As ActionResult
         ...

         ' Look up setting for custId
         ' If not found fall back on default like
         viewModel.SomeProperty = Me.mApplicationSettings.SomeDefaultValue

         Return View("...", viewModel)
    End Function
End Class

My implementation of IApplicationSettings pulls most things from the app's .config file and has a few hard-coded values in there as well.

My example wasn't logic flow-control (like your example), but it would have worked just the same if it was.

The other way to do this would be to do a service-locator type pattern, where you ask your Dependency Injection container to get you an instance of the configuration class on-the-fly. Service-Location is considered an anti-pattern generally, but might still be of use to you.