Namespace with Prefix & Suffix

namespacing to avoid state collisions:

When two attributes within the same model each have a state with the same name, there will be conflicts when creating scope and predicate methods.

In this example the class scope #draft and the instance predicate .draft? will be created as normal for the :status state_gate, but will raise an exception when creating the :invoice_status state_gate.

class Post < ActiveRecord::Base
  include StateGate

  state_gate :status do
    state :draft
    state :pending
    state :published
    state :archived
  end

  state_gate :invoice_status do
    state :draft
    state :finalised
    state :paid
  end
end

<StateGate::ConflictError>

prefix & suffix:

Theprefix and postfix options provide a mechanism to namespace states, avoiding this issue.

The prefix option prepends each state with the given name, while the suffix option appends it to the end of each state.

class Post < ActiveRecord::Base
  include StateGate

  state_gate :status do
    state :draft
    state :pending
    state :published
    state :archived
  end

  state_gate :job_status do
    state :queued
    state :processing
    state :completed

    prefix :job
  end

  state_gate :invoice_status do
    state :draft
    state :issued
    state :paid

    suffix :invoice
  end
end

Post.draft           #=> <ArctiveRecord::Relation>
Post.pending         #=> <ArctiveRecord::Relation>
Post.published       #=> <ArctiveRecord::Relation>
Post.archived        #=> <ArctiveRecord::Relation>

Post.job_queued      #=> <ArctiveRecord::Relation>
Post.job_processing  #=> <ArctiveRecord::Relation>
Post.job_archived    #=> <ArctiveRecord::Relation>

Post.draft_invoice   #=> <ActiveRecord::Relation>
Post.issued_invoice  #=> <ActiveRecord::Relation>
Post.paid_invoice    #=> <ActiveRecord::Relation>