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    <p>I would recommend creating a normal class the contains this behavior, and then let that class implement an interface extracted from the class' members.</p> <p>Whenever you need to call those methods, you inject the <strong>interface</strong> (not the concrete class) into the consumer. This lets you vary the two independently of each other.</p> <p>This may sound like more work, but is simply the <a href="http://en.wikipedia.org/wiki/Strategy_pattern" rel="nofollow noreferrer">Strategy</a> design pattern applied.</p> <p>This will also make it much easier to unit test the code, because the code is more loosely coupled.</p> <hr> <p>Here's an example in C#.</p> <p>Interface:</p> <pre><code>public interface ITimeMachine { IStopwatch CreateStopwatch(); DateTimeOffset GetNow(); } </code></pre> <p>Production implementation:</p> <pre><code>public class RealTimeMachine : ITimeMachine { #region ITimeMachine Members public IStopwatch CreateStopwatch() { return new StopwatchAdapter(); } public DateTimeOffset GetNow() { return DateTimeOffset.Now; } #endregion } </code></pre> <p>and here's a consumer of the interface:</p> <pre><code>public abstract class PerformanceRecordingSession : IDisposable { private readonly IStopwatch watch; protected PerformanceRecordingSession(ITimeMachine timeMachine) { if (timeMachine == null) { throw new ArgumentNullException("timeMachine"); } this.watch = timeMachine.CreateStopwatch(); this.watch.Start(); } public abstract void Record(long elapsedTicks); public virtual void StopRecording() { this.watch.Stop(); this.Record(this.watch.ElapsedTicks); } } </code></pre>
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    1. USMark Seemann
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    1. COThis means I should create class for handling custom functions + class for each of these functions and then simply call just execute()? So, for example, function "timeToString" would become a separate class with just execute() function, implementing interface. And I'd call it through new CustomFunction( new TimeToString ); ... $custom_function->execute() ? Is this how Strategy pattern works or do I misunderstand the concept? Isn't it a bit of overkill to create basically class for every single function?
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      1. USOndrej Slinták
    2. COYou don't have to create a class for each function. You can bundle related operations in a single class. That's what encapsulation and cehesion is all about, after all. Those operations can all be defined on the same interface, thus giving you the ability to pass around a single cohesive set of operations in a bundle.
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    3. COCould you, please, edit your post with a short example (in any language)? As I still fail to understand how exactly to do this. Should I simply create a class with multiple functions, implement an interface extracted from members and then inject this interface where ever I need it and call all those functions through it? I think what confuses me is that you mentioned Strategy pattern and I'm trying to implement the solutions exactly by it. I also don't understand why would I have an interface that is implemented by just one class. Just to prevent tight couplings by calling concrete class?
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