port select perl

[Jeremy Lavergne]

> Sounds like you're saying two things:
> 
> 1. perl should use the "port select" mechanism. I agree, and that's #29763.

My bad, another Jeremy assumption was made. It should be that versioned languages in MacPorts work this way. Alas, perl is ever so crufty. Looks like it's on the eve of being fixed though, as the last ticket update from two months ago asked for a reason to not implement the changes.

> 2. "port select" should automatically select the port being installed, if it's newer than the one that was selected. I'm not sure I agree about that. It could certainly print a message to the user advising them that this is newer and maybe they want to update their selection.

You're right: we can't do anything to migrate all packages when a newer version of a language is installed so we probably should just tell the user about the new version and do nothing until directly instructed.

The python portgroup is pretty close to being able to handle this: if the user is only ever presented with the py-* packages and a python version, MacPorts could handle switching the modules around for each version of python the user selects.