evaluationenginemodules.html

---
layout: documentation 
title: EvaluationEngine 
teaser: Decouple business logic from control flow
navigation:
   - name: Overview
     link: evaluationengine.html
   - name: Tutorial
     link: evaluationenginetutorial.html	
   - name: Modules
     link: evaluationenginemodules.html
   - name: Hierarchical Evaluation Engines
     link: evaluationenginehierarchies.html
   - name: Aggregators
     link: evaluationengineaggregators.html
   - name: Expressions
     link: evaluationengineexpressions.html
   - name: Strategies
     link: evaluationenginestrategies.html
   - name: Validation
     link: evaluationenginevalidation.html
   - name: Logging
     link: evaluationenginelogging.html
   - name: Tips and Tricks
     link: evaluationenginetipsandtricks.html
   - name: Specifications
     link: evaluationenginespecifications.html		 
---
<h2>Modules</h2>
<p>
Modules are used to load solution definitions in a modular way. 
If your dependency injection container for example allows you to acquire all classes implementing IEvaluationEngineModule, 
you can use the container to load all definitions from all your code and plug-ins automatically.
</p>

<h3>Define a Module</h3>
<p>
A module is defined by implementing <code>IEvaluationEngineModule</code>:
</p>
<script type="syntaxhighlighter" class="brush: csharp"><![CDATA[
private class FruitModule : EvaluationEngineModule
{
	protected override void Load()
	{
		this.Solve<HowManyFruitsAreThere, int>()
			.ByEvaluating(q => new FruitCountExpression { Kind = "Ananas", NumberOfFruits = 17 });
	}
}
]]></script>
<p>
When a solution is defined in several places in the code, make sure that the aggregator is only defined once.
In a plug-in system, I suggest you define the strategy and aggregator somewhere in the core. 
And the modules only add expressions.
</p>

<h3>Load Module into Evaluation Engine</h3>
<p>
Modules are loaded into the evaluation engine by calling <code>Load</code>:
</p>
<script type="syntaxhighlighter" class="brush: csharp"><![CDATA[
evaluationEngine.Load(new FruitModule());
]]></script>