Deprecate application loading in JFactory::getApplication()

[mbabker]

JFactory::getApplication() is heavily tied in to working with the legacy JApplication class, making it nearly impossible to properly refactor the method to work with the newer JApplicationBase classes. Since JFactory::getApplication() is heavily used to retrieve the application object, instead of deprecating and removing the method completely, instead I propose to deprecate its code to handle instantiating an application instance, in this case, JApplication. In 13.3 when JApplication is removed from the legacy tree, the method will be converted to throwing an Exception if the application object in JFactory is not set by applications. This allows this heavily used API to continue to be used to globally retrieve the application object.

As well, I've added a check to ensure that JApplication is present if getApplication() is actually loading an instance. Since it is in the legacy tree, there is the chance it is not present. An Exception is thrown in this instance.

[elinw]

This makes a lot of sense to me.

[elkuku]

I believe this triggers a checkstyle line length warning..

[mbabker]

The updated commit should fix that.

[eddieajau]

I'd probably go further and suggest JFactory as a whole is not something we need in the core platform anymore.

[mbabker]

You could make that argument. Once you have a JApplicationWeb instance (since that most directly replaces JApplication for that purpose), you can get the config, session, document, user (identity) and language objects out of the box. Adding support for the other objects if your application needs it is too easy. It's a matter of working away from using the factory methods I guess, and not having everyone's necks on the chopping block when the decision to deprecate it is made.

[eddieajau]

I'm just suggesting it's not needed in the core platform anymore. I would probably argue against dropping it from the CMS.

[mbabker]

I don't disagree, I'm just saying it would take some work to break the Platform of its use, the most common probably being the getApplication and getDbo methods.

[eddieajau]

Right, it's definitely a bigger job.

[davidhurley]

I agree that JFactory may not be needed in the core but think it may be a bit before that is realized. I think this commit is a good fix to move towards using JApplicationBase as opposed to the legacy class.

[LouisLandry]

This is great stuff @mbabker. I agree that JFactory is something that we need to think about. Going forward I want to see us using the application object for getting most of the things we used to get from JFactory and inject the application object into places where it is needed as a dependency. That will allow us a lot more flexibility and testability down the road.

[mbabker]

ping

Is this something we want to slip in to 12.3 or hold off for a while longer?