Iheritable/layered engines

Rails Engines Development
1

I’ve been using engines with great success doing custom shopping carts
that
rely on a core cart engine for 90% of their functionality. Every client
wants something different and it’s been a breeze pulling this off with
engines since the majority of the code never changes (warehouse,
fulfillment, management layer, etc.). What I was wondering is, we often
have clients who want two carts, that require very similar engine
overrides
(they want a public one and bulk marketing one, for example) and it’d be
great to DRY in those situations.

Are there any suggestions for layering engines so they’d act as a sort
of
base-engine? Something like this:

CompanyCart-A-Rails App < CompanyCartEngine < CoreCartEngine

CompanyCart-B-Rails App < CompanyCartEngine < CoreCartEngine

Any way of pulling something like off? Can engines use engines in the
same
way Rails Apps can use engines?

-ben

2

On 1/24/07, ben wiseley [email protected] wrote:

Are there any suggestions for layering engines so they’d act as a sort of
base-engine? Something like this:

There’s no reason why you can’t do this, if you’re careful and design
your code sensibly. The key would be to ensure that your ‘base’ is
loaded before any plugins, etc, that might override or customise it.

With 1.1.6 of the engines plugin, this would be done by ordering in
the Engines.start method:

Engines.start :core, :client, :custom

With the upcoming 1.2 release, you control load order via the
config.plugin array.