Class: Assertion::Base

Inherits:
Object
  • Object
show all
Extended by:
Attributes
Includes:
Messages
Defined in:
lib/assertion/base.rb

Overview

The base class for assertions about some attributes

Every assertion should define a list of attributes to be checked and the [#check] method to apply the assertion to those attributes

The assertion ‘call` method provides the object, describing the state of the assertion applied to its attributes. The provided state carries the result of the checkup and a corresponding <error> message. Later it can be composed with other states to provide complex validation.

The class DSL also defines shortcuts:

  • .[]

    can be used to initialize the assertion for given attributes and

    then apply it immediately with creation of the corresponding state.

  • .not

    can be used to provide the assertion opposite to the initial one.

Examples:

class Adult < Assertion::Base
  attribute :name, :age

  def check
    age >= 18
  end
end

child = Adult.not

jane = { name: "Jane", age: 12 }
Adult[jane].valid? # => false
child[jane].valid? # => true

Direct Known Subclasses

Inversion

Constant Summary

Constants included from Messages

Messages::DICTIONARY, Messages::ROOT

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Attributes

attribute

Methods included from Messages

#message

Constructor Details

#initialize(args = {}) ⇒ Base

Returns a new instance of Base.



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# File 'lib/assertion/base.rb', line 102

def initialize(args = {})
  @attributes = {}
  self.class.attributes.each { |name| __set_attribute__ name, args[name] }
  freeze
end

Instance Attribute Details

#attributes ⇒ Hash (readonly)

Returns The hash of the allowed attributes having been initialized.

Examples:

Adult = Assertion.about :name, :age do
  age >= 18
end

adult = Adult[name: "Joe", age: 15, gender: :male]
adult.attributes # => { name: "Joe", age: 15 }

Returns:

  • (Hash) —

    The hash of the allowed attributes having been initialized



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# File 'lib/assertion/base.rb', line 99

def attributes
  @attributes
end

Class Method Details

.[](hash = {}) ⇒ Assertion::State

Initializes an assertion with some attributes (data) and then calls it

Parameters:

  • hash (Hash) (defaults to: {})

Returns:

  • (Assertion::State) —

    The object that describes the state of the assertion applied to given attributes



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# File 'lib/assertion/base.rb', line 53

def [](hash = {})
  new(hash).call
end

.not ⇒ Assertion::Inverter

Initializes the intermediate inverter with ‘new` and `[]` methods

The inverter can be used to initialize the assertion, that describes just the opposite statement to the current one

Examples:

Adult = Assertion.about :name, :age do
  age >= 18
end

joe = { name: 'Joe', age: 19 }

Adult[joe].valid?     # => true
Adult.not[joe].valid? # => false

Returns:



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# File 'lib/assertion/base.rb', line 74

def not
  Inverter.new(self)
end

Instance Method Details

#call ⇒ Check::State

Calls the assertion checkup and returns the state of the assertion having been applied to the current attributes

Returns:

  • (Check::State) —

    The state of the assertion being applied to its attributes



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# File 'lib/assertion/base.rb', line 114

def call
  state = check
  State.new state, message(false)
end