Re: Re: Scope woe

On Tue, Jun 30, 2009 at 12:37 PM, Paul M Foster<paulf@quillandmouse.com> wrote: > On Tue, Jun 30, 2009 at 11:17:17AM -0400, Eddie Drapkin wrote: > > <snip> > >> >> I wouldn't really recommend going with a singleton in this situation, >> as there exists a different solution (my other post :P) and there are >> very few actual use-cases where the pattern makes sense, and deploying >> it unnecessarily can cause a whole lot of headache D: >> > > I disagree. A singleton is quite a good solution, particularly when you > only want one instance of an object. You can also create a "registry" > class which contains instances of objects which might be useful to other > classes. > > Why would a singleton lead to headaches? > > Paul > -- > Paul M. Foster > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > If you only want one instance of a class at any point, that's the whole purpose of the pattern, so how could I argue against that? All I said was it's really rare that there's a justifiable reason (and in the above example, it's simply to compensate for not wanting to handle it elsewhere i.e. laziness) to actually use the pattern. A lot of the times you see singletons in use, it's for ease of use, not functionality; database layers, for example, have no necessity of being singletons and it's restrictive to do so, yet it's done all the time. For a generic question like this, suggesting a single design pattern as the solution is a bad idea, as someone who doesn't know better will assume it's the only solution, thus leading to those headaches of dealing with a misapplied paradigm to a particular situation. As far as the registry class paradigm goes, it's occasionally useful, as is the singleton pattern, but it's not a solution I'd necessarily recommend because of the overhead implications, especially not in such a simple situation as storing an instance in a static variable.