[Owncloud] App Requirements

[Robin Appelman]

On Thursday 19 April 2012 16:52:33 Klaas Freitag wrote:
> > But we could make this even possible for PHP libraries etc.
> 
> Yes. Well. I know most of you don't want to hear and face it, but we're
> talking about to reimplement a dependency system of software packages.
> There are already systems that cover that. See every Linux distro.
> 
> I really suggest to stay away from reimplementing that. Its hell.
> 
> I agree we need something for the apps. But for all system dependant
> stuff such as php extensions and programs, I would try to reuse the
> underlying package system until we have a huge coding community.
> Currently we will loose ourselfes.
> 
> Maybe we can and should maintain a list of packages per distro times
> distro-version which package names are needed for the app, together with
> a function that is provided by the module. If a call to that fails, we
> can say its not there.
> Than we could either install (if the user is allowed which is off by
> default probably) but at least we can give a good error message to the
> one who installs.
> 
> For the beginning, I would leave it with a "This app requires the PHP GD
> module. Please make sure to install it."
> 
> I'd rather suggest to work on getting also the apps properly packaged
> for the distros so that problem goes away naturally.
> 
> Klaas

We don't need to re-implement a full dependency system, we just need to check 
if a certain function/class is available or check if a php module is loaded 
and don't enable the app if that isn't the case.

All those checks are one-liners in php and we just need a way for apps to 
describe the list of non-default functions/classes/module they need

 - Robin Appelman