Determine before installation whether a port can be installed

[Ryan Schmidt]

On Jul 28, 2016, at 9:18 AM, Ken Cunningham wrote:

> OK -- So - I am absolutely nobody at all on this list, so please take this following idea gently.
> 
> This work you're embarking on (specifying what systems a given port will build on, and which it won't) would seem in fact to be very similar to what I was getting at when I asked about the 'distributions' idea in that ticket I opened a few weeks ago.
> 
> The only extra part of this that I was hoping for would the ability to peek back in the port file history and find (and install) the last version of a port file (apache2, say) that was able to be installed on a given system (like SL). 
> 
> This ability would solve a lot of troubles for older systems, although there could be the same dependencies issues that this idea will generate as well, perhaps.
> 
> As macports moves forward, the caboose of which machines are left behind will continue to move forward as well. But there are working portfiles back there that are still good...
> 
> My $0.02.

These are interesting ideas, but would require major changes* to MacPorts and don't relate to the issue I'm trying to discuss in this thread.



* MacPorts currently has no idea that Portfiles have a "history"; it has no idea that Portfiles live in a Subversion repository and that earlier versions of a Portfile exist.

* MacPorts currently does not support users who install older versions of Portfiles. It may work, but if it does not, the user is on their own.

* The MacPorts project currently makes no guarantees that an old version of a Portfile is installable on the current version of MacPorts, and there have been many situations in the past where indeed old Portfiles cannot be used on current versions of MacPorts without manual changes.