Install-Package ExistForAll.SimpleSettings

1.Introduction
2.Getting started
3.Building the collection
4.Building Config Interfaces
5.DefaultValue
6.Build Section Binders
7.Extending SimpleConfig

With the release of Asp.Net Core and .Net Core Microsoft has introduced IOptions<>. While IOptions<> is a great concept it lacks in implementation. IOptions<> provide a way to insert parameters into your app dynamically.

For example you have an email service that requires some URL to the email server.

public class EmailSender
{
    public EmailSender(string emailServiceUrl, ... )
    {

    }
}

All of the good IOC containers out there will tell you that injecting a string into a service is a bad idea. The best of them won't let you do it.

IOptions<> to the rescue, with IOptions<> you can request the option class that can provide the string you want provided from any data store you want (json file, database and so on).

public class EmailSender
{
    public EmailSender(IOption<EmailProviderConfiguratation> configuration, ... ) { }
}

BUT IOptions<> is not the way to do this.

Why you ask ?

1. As Uncle Bob said, your application must be independent from frameworks this the application code takes an unnecessary dependency on a framework abstraction, this is a violation of DIP.
2. In order to inject IOption<SomeClass> SomeClass have to be a concrete class and not an interface.
3. To use IOption<SomeClass> you must call services.Configure<SomeClass> in the Setup class, this is not scale-able in any way and the last thing we want to do is to manually configure each configuration class.
4. Registering IOption<> in any other DI container different from Microsoft new DI container won't be a ball park.

For better understanding you can read this explenation from the SimpleInjecor docs.

Remember the IOption<EmailProviderConfiguratation> configuration?

what if we could build an interface like so

public interface IEmailServiceConfig
{
    [DefaultValue("SomeUrl")]
    string ServiceUrl {get; set;}
}

and use it like so

public class EmailSender : IEmailSender
{
   public EmailSender(IEmailServiceConfig emailServiceConfig, ... ) { }

   public void SendEmail(...)
   {
        Send(emailServiceConfig.ServiceUrl, ...);
    }
}