Bitter Coder - Part 1 - Simple configuration

Tuesday, April 17, 2007

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: 12.50

Now, 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...

castle | IoC

posted @ Tuesday, April 17, 2007 7:16:25 AM (New Zealand Standard Time, UTC+12:00) Comments [0] | Trackback | Tracked by:
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