Allow mapping to take a path as argument

[jodosha]

When we configure Lotus::Model, it would be great to make mapping to accept a path where to find the mapping definitions.

Lotus::Model.configure do
  adapter type: :memory, uri: 'memory://localhost'
  mapping 'config/mapping'
end.load!

# config/mapping.rb
collection :users do
  # ...
end

We already support this syntax in lotusrb for routes definitions.

[runlevel5]

@jodosha I find this feature duplicated with mapping DSL in lotusrb. Are you sure on this?

[jodosha]

@joneslee85 Sorry for the late reply. Yes I'm sure ;)

In the "container" architecture we have:

# ...
apps/
  backend/
  web/
lib/
  bookshelf.rb
  entities/
  repositories/
  interactors/

That lib/ directory implements the application use cases, independently from the delivery mechanism (aka the web apps under apps/). While the Lotus slices use something like this:

module Web
  class Application < Lotus::Application
    configure do
      mapping # path or block
    end
  end
end

The lib part just deals with plain objects and eventually the persistence. So that lib/bookshelf.rb may want to use top level Lotus::Model:

Lotus::Model.configure do
  mapping # we only have block, but we want path too.
end

For instance we may want to load definitions from lib/config/mapping.rb.
Does it makes sense?