If your utilities and helpers are not specific to Symfony, create the library in a separate repo and install it to the suppliers using deps
using the bin/vendors install
or through Composer , which will become the standard way to manage suppliers with Symfony 2.1.
If you want your library to integrate seamlessly with Symfony, create the package in another separate repo and install it to the providers. Thus, your library can be used outside of Symfony projects, but when used in Symfony, it provides some convenience.
Also see a few questions.
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