Foundations of Programming - Karl Seguin

Chapter 4 - Dependency Injection
While I don’t want to spend too much time talking about configuration, it’s important to note that the
XML file must be deployed in the /bin folder of your application. You can automate this in VS.NET by
selecting the files, going to the properties and setting the Copy To Ouput Directory attribute to Copy
Always. (There are a variety of more advanced configuration options available. If you’re interested in
learning more, I suggest the StructureMap website).
Once configured, we can undo all the changes we made to the Car class to allow constructor injection
(remove the _dataProvider field, and the constructors). To get the correct IDataAccess
implementation, we simply need to ask StructureMap for it, the Save method now looks like:
public class Car
{
private int _id;
}
public void Save()
{
if (!IsValid())
{
//todo: come up with a better exception
throw new InvalidOperationException("The car must be in a valid
state");
}
}
IDataAccess dataAccess = ObjectFactory.GetInstance();
if (_id == 0)
{
_id = dataAccess.Save(this);
}
else
{
dataAccess.Update(this);
}
Foundations of Programming Copyright © Karl Seguin www.codebetter.com
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