Question

I am currently working on a project where I need to create objects at runtime based on a configuration file.

Project example

Here is a simplified example of the project I am working on.

Every object created must implement a specific interface, let it be called the IObjectInterface for the example purpose :

public interface IObjectInterface
{
    void DoSomething();
}

Let’s assume that I have several classes that implement this interface, each having a specific implementation, and multiple other properties relevant to the specific type :

public class SimpleObject : IObjectInterface
{
    public void DoSomething()
    {
        Console.WriteLine("SimpleObject did something");
    }
}

public class ComplexObject : IObjectInterface
{
    public string ObjectName { get; set; }

    public void DoSomething()
    {
        Console.WriteLine("The ComplexObject named {0} did something", this.ObjectName);
    }
}

public class VeryComplexObject : IObjectInterface
{
    public string ObjectName { get; set; }
    public bool CanDoSomething { get; set; }

    public void DoSomething()
    {
        if (this.CanDoSomething)
        {
            Console.WriteLine("The ComplexObject named {0} did something", this.ObjectName);
        }
        else
        {
            Console.WriteLine("The ComplexObject named {0} tried to do something, but was not allowed to", this.ObjectName);
        }
    }
}

I need to be able to create a IObjectInterface object corresponding to a specific Id using the ObjectBuilder class :

public class ObjectBuilder
{
    IObjectInterface BuildObject(string objectId)
    {
        // Build object here based on provided Id
    }
}

What I am looking for is a way to specify, in a configuration file, the correct implementation of IObjectInterface that should be created, and the parameter values associated to the specific type.
The ideal configuration file should look like this :

<objects>
 <object id="Simple">
  <objectInterface type="SimpleObject" />
 </object>
 <object id="Complex">
  <objectInterface type="ComplexObject">
   <ObjectName value="MyObject" />
  </objectInterface>
 </object>
</objects>

I think I should be able to manage the object instantiation part, but I don’t really see how I can manage the initialization of the instances with clean code.

• Do you have some leads on how I can implement such a configuration file ?
• How can I easily create the final instances of the needed objects and initialize them with the parameters provided in the configuration file ?
• Are there any frameworks that could help me implementing a solution to my problem ?

Answer 1

Sounds like IOC for me. StructureMap NInject Microsoft Extensibility Framework