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POUsing singleton instead of a global static instance
 

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    <p>I ran into a problem today and a friend recommended I use a global static instance or more elegantly a singleton pattern. I spent a few hours reading about singletons but a few things still escape me.</p> <p>Background: What Im trying to accomplish is creating an instance of an API and use this one instance in all my classes (as opposed to making a new connection, etc).</p> <p>There seems to be about 100 ways of creating a singleton but with some help from <a href="http://www.yoda.arachsys.com/csharp/singleton.html" rel="noreferrer" title="aka Jon Skeet">yoda</a> I found some thread safe examples. ..so given the following code:</p> <pre><code>public sealed class Singleton { public static Singleton Instance { get; private set; } private Singleton() { APIClass api = new APIClass(); //Can this be done? } static Singleton() { Instance = new Singleton(); } } </code></pre> <p>How/Where would you instantiate the this new class and how should it be called from a separate class?</p> <p>EDIT: I realize the Singleton class can be called with something like</p> <pre><code>Singleton obj1 = Singleton.Instance(); </code></pre> <p>but would I be able to access the methods within the APIs Class (ie. obj1.Start)? (not that I need to, just asking)</p> <p>EDIT #2: I might have been a bit premature in checking the answer but I do have one small thing that is still causing me problems. The API is launching just fine, unfortunately Im able to launch two instances?</p> <p>New Code</p> <pre><code>public sealed class SingletonAPI { public static SingletonAPI Instance { get; private set; } private SingletonAPI() {} static SingletonAPI() { Instance = new SingletonAPI(); } // API method: public void Start() { API myAPI = new API();} } </code></pre> <p>but if I try to do something like this...</p> <pre><code>SingletonAPI api = SingletonAPI.Instance; api.Start(); SingletonAPI api2 = SingletonAPI.Instance; // This was just for testing. api2.Start(); </code></pre> <p>I get an error saying that I cannot start more than one instance.</p>
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    1. USJohn Saunders
    1. USRyan
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    1. COYou should add a private constructor, as well, to prevent another class from instantiating a copy of your Singleton.
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      1. USReed Copsey
    2. COThank you, I missed that.
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      1. USRyan
    3. COYou won't be able to call methods on the api class, because it is not being exposed.
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      1. USJohn Buchanan
 

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