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POConfusion about DI, IoC and service locators
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copied!<p>I have read various articles about IoC, DIP, DI and Service Locators but I'm a bit confused which is which because some articles have too vague examples and some other articles have just some specific examples without mentioning other cases. </p> <p><strong>Could you please clear this up for me, looking at the examples below and shortly explaining which examples match which pattern?</strong></p> <ul> <li><p>manually passing interface to constructor:</p> <pre><code>class Consumer { public Consumer(IStore store){...} } ... Consumer c = new Consumer(new ConcreteStore()); </code></pre></li> <li><p>the same as the first example but using some 3rd party library (Unity, Windsor, Ninject)</p></li> <li><p>the same as the first example but using BaseStore class instead of IStore interface</p></li> <li><p>passing dependency to some other method, not to constructor:</p> <pre><code>class Consumer { public BySomething(IStore store){...} } ... Consumer c = new Consumer(); c.BySomething(new ConcreteStore()); </code></pre></li> <li><p>passing dependencies masked inside of some other interface (bonus for this solution - when some other things are invented in the "world" and Consumer wishes to use them, we don't have to change constructor argument but just update IWorld; and we can completely replace entire World with something else when testing):</p> <pre><code>interface IWorld { IDictionary<string,IStore> Stores { get; set; } IDictionary<string,ICityMap> Maps { get; set; } ... } class Consumer { public Consumer(IWorld world){...} public BySomething(string store, string city){...} } ... IWorld myWorld = new HeavenlyWorld(); ... // adding stores, maps and whatnot Consumer c = new Consumer(myWorld); </code></pre> <p>a sub-question: in this case, is IWorld a service locator or not exactly?</p></li> <li><p>passing a call-back function or delegate (.NET Action in this case):</p> <pre><code>c.BySomething(store, city, new Action(() => {...} )); </code></pre> <p>I added this case because the article <a href="http://devmethodologies.blogspot.com/2012/06/inversion-of-control.html" rel="nofollow">Inversion of Control</a> states that every callback is IoC. Is it true?</p></li> </ul>

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