Purpose of singletons in programming

Question

This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever crea

Answer 1

why you would wan't to

I wouldn't because singletons usually are very bad way to solve your problems. My recommendation to you is to avoid them completely.

The main reasons are:

• Singletons mostly represent global state (which is evil).
• Correct dependency injection becomes impossible.

I suggest you read the rest (including thorough explanations) in this Google employee's blog:

• http://misko.hevery.com/2008/08/17/singletons-are-pathological-liars/
• http://misko.hevery.com/2008/08/21/where-have-all-the-singletons-gone/
• http://misko.hevery.com/2008/08/25/root-cause-of-singletons/
• http://misko.hevery.com/code-reviewers-guide/flaw-brittle-global-state-singletons/