Module: Condi

Defined in:

lib/condi.rb

Overview

Include this module in an ActionController to define predicates or synonyms within an action context that can be used later in the related action view.

Examples:

class StoreController
  include Condi
  ...
end

Instance Method Summary

• #predicate(method_name, &block) ⇒ Object (also: #synonym)

  define a method on the controller which is callable from the related view and returns a true or false value.

Instance Method Details

#predicate(method_name, &block) ⇒ Object Also known as: synonym

Note:

A synonym is an alias for defining methods that return values other than true or false.

Note:

You are not required to end a predicate with a question mark, however it is conventional in Ruby to do so.

define a method on the controller which is callable from the related view and returns a true or false value.

Examples:

define a predicate that determines whether or not to show a “free shipping” option.

predicate(:show_free_shipping?) { user.new_customer? && cart.amount > 100 }

define a predicate that takes an element of a collection as an argument.

predicate(:shipping?) { |item| @items.count >= 3 && 
   item.status == :shipped && 
   DeliveryService.status(item.tracking_number) !~ /arrived/ }

define a synonym that returns a css class based on item status

synonym(:css_for_item_status) do |item| 
  if @items.count >= 3 && item.status == :shipped 
    if DeliveryService.status(item.tracking_number) !~ /arrived/
      "shipping"
    else
      "shipped"
    end
  else
    "processing"
  end
end

Parameters:

• method_name (Symbol) —

  name of the predicate or synonym method. (e.g. :show_action_button?)

• block (Proc) —

  {} or do…end block.

See Also:

• full example in the README.

# File 'lib/condi.rb', line 34

def predicate(method_name, &block)
  self.class.instance_eval do
    define_method(method_name, &block)
    helper_method(method_name)
  end
end