How to instantiate a persistent Singleton

[Guest]

I have a data access component for accessing non-relational data stores, and in order to make it useful, I need to enable pooling. What would work best would be if I could instantiate a singleton class when starting coldfusion, but I have no idea how to do that. Is there a way to instantiate a class that persists through the life of the server, or even through the life of a session? The latter would be more of a work-around but I could probably live with it.

Any help would be appreciated.

[Stressed_Simon]

You can instantiate the object in application scope. I recommend not instantiating objects in session scope as it can get out of hand and cause memory problems.

[Grizzly9279]

Stressed_Simon's recommendation is a good one. Caching a stateless "singleton" class in the application scope is the best way to accomplish this. We do this quite a bit for our DAO's.

Though not strictly required, you can streamline access to your application-scoped singleton CFCs using a framework like ColdSpring:
http://www.coldspringframework.org

Best of luck.

[Guest]

Can someone point me at sample code to do this? I'm new to cfscript and while I found lots of talk about variable scope, I found precious few useful examples of how to create a variable of server or application scope and then reference it.

Thanks,

[Stressed_Simon]

application.myObj = createObject("component", "path.to.cfc");

[Guest]

Hmmm. I'm not getting something here. Is there a special place that I put this? If I put this in script on my page, doesn't it create a new instance of my object every time? I really wanted just one instance of the object. Guaranteed one instance, but only one.

I may have found what I'm looking for here:
http://www.webtricks.com/sourcecode/code.cfm?CodeID=25
It looks a bit complex, but I think it might work.

[Stressed_Simon · Accepted solution]

OK if you are using Application.cfm then the following:-

If (NOT structKeyExists(application, "myObj")) {
application.myObj = createObject("component", "path.to.cfc");
{

if you are using Application.cfc then the following in then onApplicationStart() function:-

application.myObj = createObject("component", "path.to.cfc");

If you aren't using either then you should be!!!!

[Guest]

Thanks, I think that's what I was missing.