Welcome to part 1... today we're looking at supporting basic configuration in components without additional coding by using the windsor container.
So - with the container we can provide configuration for a component which is loaded at runtime, so every time you start your app it will be read in - you can do this using the configuration support in .Net - but using castle makes support for this very code-light in comparison... let's take a look.
So first off, we have a class we can use to calculate the tax on a gross ammount:
public class TaxCalculator
{
private decimal _rate = 0.125m;
public decimal Rate
{
set { _rate = value; }
get { return _rate; }
}
public decimal CalculateTax(decimal gross)
{
return Math.Round(_rate*gross, 2);
}
}
By default the tax rate is 12.5% - but we can change the tax rate by setting the "Rate" property.
Now, lets look at setting up the container... so we have this code in our sample:
private static void Main(string[] args)
{
WindsorContainer container = new WindsorContainer(new XmlInterpreter());
TaxCalculator calculator = container.Resolve<TaxCalculator>();
decimal gross = 100;
decimal tax = calculator.CalculateTax(gross);
Console.WriteLine("Gross: {0}, Tax: {1}", gross, tax);
Console.Read();
}
The windsor container is constructed with an "XmlInterpreter" - this configuration will pull the setup for our container from a section in the App.config.
Let's have a look at that:
<configuration>
<configSections>
<section name="castle"
type="Castle.Windsor.Configuration.AppDomain.CastleSectionHandler, Castle.Windsor" />
</configSections>
<castle>
<components>
<component id="taxcalc.service" type="IoC.Tutorials.Part1.TaxCalculator, IoC.Tutorials.Part1" />
</components>
</castle>
</configuration>
Running the program will display:
Gross: 100, Tax: 12.50Now, what about changing the tax rate in the configuration?
<configuration>
<configSections>
<section name="castle"
type="Castle.Windsor.Configuration.AppDomain.CastleSectionHandler, Castle.Windsor" />
</configSections>
<castle>
<components>
<component id="taxcalc.service" type="IoC.Tutorials.Part1.TaxCalculator, IoC.Tutorials.Part1">
<parameters>
<Rate>0.25</Rate>
</parameters>
</component>
</components>
</castle>
</configuration>
Now running the program will display: Gross: 100, Tax: 25.00
And that's part 1 done - so now you can see how can we supply configuration parameters, and provide sensible defaults for them.
Next time we'll look at configuring arrays...