Moving from Factory Pattern to IoC - inversion-of-control

Question

So I understand IoC, especially when "injecting an unknown concrete" into a class.
The most generic example of injecting an "ILogger" into a class either in the constructor or by a property.
Now, I have a older Factory Pattern, that I'm trying to figure out how/if I can convert to IoC. (I am using Unity, fyi).
Below I have my older Factory pattern. It basically makes a factory decision based on the current price of gas (petro). If gas is really expensive, I'm riding my bicycle. If gas is medium priced, I'm driving the car. If gas goes cheap, then I'm driving my truck to work!
(Its a dumb example, just roll with it, please).
What I don't understand is how I "translate" this into IoC......when it comes to making a business-logic decision on which concrete class is returned.
What am I missing?
Maybe I still need a factory? Or am I missing some key concept?
Thanks in advance for any help...
namespace MyApp
{
public interface IVehicle
{
void MakeTrip();
}
public class Bicycle : IVehicle
{
public void MakeTrip() { Console.WriteLine("Bicycles are good when gas is expensive."); }
}
public class Car : IVehicle
{
public void MakeTrip() { Console.WriteLine("Cars are good when gas is medium priced"); }
}
public class PickupTruck : IVehicle
{
public void MakeTrip() { Console.WriteLine("Gas is back to 1980's prices. Drive the truck!"); }
}
public static class VehicleFactory
{
public static IVehicle GetAConcreteVehicle(decimal priceOfGasPerGallon)
{
if (priceOfGasPerGallon > 4.00M)
{
return new Bicycle();
}
if (priceOfGasPerGallon > 2.00M)
{
return new Car();
}
return new PickupTruck();
}
}
public class TripControllerOldFactoryVersion
{
public decimal PriceOfGasPerGallon { get; set; }
public TripControllerOldFactoryVersion(decimal priceOfGas)
{
this.PriceOfGasPerGallon = priceOfGas;
}
public void TakeATrip()
{
IVehicle v = VehicleFactory.GetAConcreteVehicle(this.PriceOfGasPerGallon);
v.MakeTrip();
}
}
}
class Program
{
static void Main(string[] args)
{
try
{
TripControllerOldFactoryVersion controller1 = new TripControllerOldFactoryVersion(5.00M);
controller1.TakeATrip();
TripControllerOldFactoryVersion controller2 = new TripControllerOldFactoryVersion(3.33M);
controller2.TakeATrip();
TripControllerOldFactoryVersion controller3 = new TripControllerOldFactoryVersion(0.99M);
controller3.TakeATrip();
}
catch (Exception ex)
{
Exception exc = ex;
while (null != exc)
{
Console.WriteLine(exc.Message);
exc = exc.InnerException;
}
}
finally
{
Console.WriteLine("Press ENTER to Exit");
Console.ReadLine();
}
}
}
So the above is the Factory version.
So I'm trying to figure out what the best way is to convert this to IoC, but still have some "based on the price of gas" logic for determining the IVehicle.
Starter code is below.
public class TripControllerIoCVersion
{
public IVehicle TheVehicle { get; set; }
public TripControllerIoCVersion(IVehicle v)
{
this.TheVehicle = v;
}
public void TakeATrip()
{
if (null != this.TheVehicle)
{
this.TheVehicle.MakeTrip();
}
}
}

Answer 1

Well. I figured out something. I still need to think about it.
I don't like the hardcoded "key" names. But it does work.
The code above is still needed, but I changed my "factory" to the below.
First, the unity configuration.
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration"/>
</configSections>
<unity>
<container>
<register type="MyProjectName.IVehicle, MyProjectName" mapTo="MyProjectName.Bicycle, MyProjectName" name="myBicycleKey" />
<register type="MyProjectName.IVehicle, MyProjectName" mapTo="MyProjectName.Car, MyProjectName" name="myCarKey" />
<register type="MyProjectName.IVehicle, MyProjectName" mapTo="MyProjectName.PickupTruck, MyProjectName" name="myPickupTruckKey" />
</container>
</unity>
</configuration>
Now the cs code.
public static class VehicleFactory
{
public static IVehicle GetAConcreteVehicle(decimal priceOfGasPerGallon)
{
var container = new UnityContainer();
UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
section.Configure(container);
IVehicle v = null;
if (priceOfGasPerGallon > 4.00M)
{
v = container.Resolve<IVehicle>("myBicycleKey");
return v;
}
if (priceOfGasPerGallon > 2.00M)
{
v = container.Resolve<IVehicle>("myCarKey");
return v;
}
v = container.Resolve<IVehicle>("myPickupTruckKey");
return v;
}
}
I guess I got the idea from here:
http://www.sharpfellows.com/post/Unity-IoC-Container-.aspx