gpsbabel suddenly based on qt5-mac thus leaving qt4-mac-based port qlandkartegt in limbo

[Ryan Schmidt]

On Jun 10, 2015, at 3:39 AM, René J. V. Bertin wrote:
> 
> Marko Käning wrote:
> 
>> How to transition from Qt4 to Qt5 more smoothly?? This is going to happen for
>> many ports in the future, so, perhaps this is a port where one could try to
>> exercise how to do it least disturbingly for users having installed qt4-mac
>> ports?!
>> 
>> I - for my part - am still having a fully qt4-mac-based MacPorts system for
>> production, which is why I don’t want such automagic transitions to Qt5,
>> unless all dependent ports have also migrated to Qt5.
>> 
>> Any ideas?
> 
> Yeah, good luck with that.
> What you want is a system that detects what the user has installed and adapts 
> dependencies.

I don't think Marko is saying that. He's saying he wants to be able to upgrade his ports and have them still work. That's reasonable.

> The times I tried that my efforts were rejected because behaviour 
> has to be deterministic. I implemented a port select feature for my own Qt4 and 
> Qt5 ports, but apparently that's verboten too for ports that are dependencies 
> for other ports (maybe because it's "implicit/hidden indeterminism").
> You'd have to figure in the fact that not all projects will continue to provide 
> the option to build against either Qt4 or Qt5 for as long as you'll want, partly 
> because the transition to Qt5 has been going on quite a bit longer than what one 
> might deduce from its presence in MacPorts.

You are correct, we don't want ports building themselves differently based on what other ports are installed.


> Your best long-term option will be to configure your own port repository in which 
> you keep the last "desirable" version of ports that no longer correspond to your 
> requirements (a priori you should be able to do that with minimal modification if 
> at all).

I don't think we should be recommending maintaining a local ports repository as a solution for users. It is meant for port developers to test their ports before they are added to the main repository.


Seems the first step in providing any smooth migration from qt4 to qt5 (for those ports that support that, while still allowing those that don't to remain on qt4) is to make qt4 and qt5 simultaneously installable:

https://trac.macports.org/ticket/44193

Seems some action has happened on that ticket lately, though I see you're already aware of that ticket.