If Symfony are the only framework to use it then Packist is just going to be full of their code and not a lot else.
We use Pearfarm internally for all of our shared code, and it's super-easy to build and share packages.
Frankly I don't understand why something like Pearfarm hasn't been widely adopted, since it is essentially the same as RubyGems which is a completely workable solution for the ruby community.
I think people just don't understand that PEAR has 2 parts, the "installer" and the "official repo" and basically they write off anything related to PEAR.
In any case I'd love to hear your thoughts on why the community doesn't rally around Pearfarm, Pearhub, etc since they are basically the solution you're looking for.
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Just give it a shot, forget how it's built, use it and please give us feedback/report issues. We're improving things on a daily basis.
It uses the process, console, and autoloader components. That being said, as a user, you need not worry about that. You put the composer.phar somewhere and invoke it.
If that isn't more useable than pyrus, I'd be interested to here what is.
While I do agree that there is a need for a real packaging system for PHP, I don't think Composer/Packagist is the answer.
Packaging is a real hard "exercise", I've dabbled with it, and it's certainly not an easy problem. Composer/Packagist is still not there yet and its ties to Symfony are "scaring" off developers (myself for example).
If it wasn't for the outdated code, the bad peer review system, PEAR is the closest thing we have, as PHP developer, of a working packaging system. If only the PHP team would invest a bit of time to modernize it and make it relevant again, I'd give it a go for sure.