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POHow should I refactor my code to remove unnecessary singletons?
 

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  1. POHow should I refactor my code to remove unnecessary singletons?
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    <p>I was confused when I first started to see anti-singleton commentary. I have used the singleton pattern in some recent projects, and it was working out beautifully. So much so, in fact, that I have used it many, many times.</p> <p>Now, after running into some problems, reading <a href="https://stackoverflow.com/questions/137975/what-is-so-bad-about-singletons">this</a> SO question, and especially <a href="http://steve.yegge.googlepages.com/singleton-considered-stupid" rel="nofollow noreferrer">this</a> blog post, I understand the evil that I have brought into the world.</p> <p>So: How do I go about <i>removing</i> singletons from existing code?</p> <p>For example:<br> In a retail store management program, I used the MVC pattern. My Model objects describe the store, the user interface is the View, and I have a set of Controllers that act as liason between the two. Great. Except that I made the Store into a singleton (since the application only ever manages one store at a time), and I also made most of my Controller classes into singletons (one mainWindow, one menuBar, one productEditor...). Now, most of my Controller classes get access the other singletons like this:</p> <pre><code>Store managedStore = Store::getInstance(); managedStore.doSomething(); managedStore.doSomethingElse(); //etc. </code></pre> <p>Should I instead:</p> <ol> <li>Create one instance of each object and pass references to every object that needs access to them? <li>Use globals? <li>Something else? </ol> <p>Globals would still be bad, but at least they wouldn't be <a href="http://misko.hevery.com/2008/08/17/singletons-are-pathological-liars/" rel="nofollow noreferrer">pretending</a>.</p> <p>I see #1 quickly leading to horribly inflated constructor calls:</p> <pre><code>someVar = SomeControllerClass(managedStore, menuBar, editor, sasquatch, ...) </code></pre> <p>Has anyone else been through this yet? What is the OO way to give many individual classes acces to a common variable without it being a global or a singleton? </p>
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    1. USe.James
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    1. COWould you care to elaborate on what kind of problems you are running into?
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      1. POHow should I refactor my code to remove unnecessary singletons?
      1. USOtávio Décio
    2. COYeah, I'd like to see a more concrete example of the things you're making into Singletons. Maybe it's not a problem after all?
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      1. USOutlaw Programmer
    3. CO'refactor', isn't that moving/renaming code around? You're probably looking to rewrite your code.
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      1. USfalstro
 

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