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The requirements for Factories has changed a lot since the long discussion on #1793 and #1219 :

• Factories will no longer be exposed publicly. They will constitute a completely internall API to be used by the Timber\Timber class.
• Instead of exposing Factories externally, we're exposing a small set of filters that will be used inside Factories to instantiate the correct class for a given post type, taxonomy, etc.
• The requirements for Factories is now being driven by the new API proposal for Timber::get_posts() and friends.

Goals

The goals for implementing Factories are:

• To provide a centralized layer for instantiating Timber\Core instances (Post, Term, etc.) and their corresponding collection classes (e.g. PostCollection).
• To eventually replace PostGetter etc., to be called directly from Timber::get_* methods (e.g. ::get_posts).
• To provide a centralized place to implement filters like timber/post/classmap as described in the Class Map proposal.
• To incorporate the best ideas from WIP: Feature/interfaced object factories #1793 and Object factory usage #1219 in a way that matches up with the new API proposal