ActionView::AbstractRenderer

This class defines the interface for a renderer. Each class that subclasses AbstractRenderer is used by the base Renderer class to render a specific type of object.

The base Renderer class uses its render method to delegate to the renderers. These currently consist of

PartialRenderer - Used for rendering partials
TemplateRenderer - Used for rendering other types of templates
StreamingTemplateRenderer - Used for streaming

Whenever the render method is called on the base Renderer class, a new renderer object of the correct type is created, and the render method on that new object is called in turn. This abstracts the setup and rendering into a separate classes for partials and templates.