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The Singleton Pattern: To be or not to be [used]?

Aaron Carter · 2012-11-14T14:13:27

I'm aware of the numerous problems that can arise through the use of the Singleton pattern, which some go as far as calling an anti-pattern... One of the biggest problems is all the references to the global instance/state, for example: [source lang="csharp"] // inside method body... var obj = Something.Get(); obj.TakeAction(); obj.Whatever(); [/source] This can really complicate testing and make code that's difficult to maintain... However, I'm wondering if the Singleton pattern is not ok (or even optimal) for certain circumstances when only one, globally accessible instance of something should exist... Consider the class I'm currently working on. It is called "NativeMemoryManager", and it is essentially a "safe" API for allocating, manipulating and releasing unmanaged process memory within a .NET application (it uses a 1:1 wrapper I wrote of the CRT memory management API as its back-end -- this is all part of my generalized application & game development framework). NativeMemoryManager inherits "DisposableObject", which is an abstract class that offers a robust implementation of the IDisposable interface; all instances of which are pushed into the "ObjectTable" which is traversed at application shutdown to destroy potential memory leaks... Only one instance of NativeMemoryManager should ever exist. It's only field is a data table which stores critical information about all memory allocations to prevent memory errors and free any unfreed memory when the application is shutdown. It doesn't need multiple states, and I don't foresee myself ever wanting to replace the singleton instance with some sort of testing instance. Also, if I implement any objects which need to use/consume NativeMemoryManager I will make that object accept the instance in its constructor and store it locally: [source lang="csharp"] public SomeType( NativeMemoryManager mem ) { this.nativeMem = mem; } [/source] Then it will use the reference its stores rather than calling NativeMemoryManager.Obtain() over and over... So considering this particular case and others like it, do you see any problem with using the Singleton pattern? Or is there a better way to approach this?

General and Gameplay Programming Programming

Started by ATC November 07, 2012 12:25 PM

79 comments, last by 21st Century Moose 11 years, 5 months ago

21st Century Moose

13,459

November 14, 2012 02:13 PM

This one is also worth reading: http://tech.puredanger.com/2007/07/03/pattern-hate-singleton/

Cool quote:

First, it is important to separate the “need for one of something in my system” from the “singleton pattern”. It’s perfectly reasonable to want one of something but to avoid using the singleton pattern. In other words, the problem is in the pattern, not in the goal.[/quote]

Direct3D has need of instancing, but we do not. We have plenty of glVertexAttrib calls.

The Singleton Pattern: To be or not to be [used]?

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The Singleton Pattern: To be or not to be [used]?

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