NeuronCheck has a simple plug-in mechanism, and users can add original keywords for declaration in addition to built-in keywords.

For example, if you want to add the new keyword boolean, please describe in the following manner.

require 'neuroncheck'

NeuronCheckSystem::Plugin.add_keyword(:boolean) do
  # Method that is called when you use the keyword
  # if it is called a keyword in with arguments like `respondable(:each)`, is it also passed as an argument to the on_call method
  def on_call

  # Method to perform the actual check processing. There is a need to return either true or false
  def match?(value)
    value.equal?(true) or value.equal?(false)

  # String that represents the contents of the keyword. It is used in the error message
  def expected_caption
    "boolean value"

Among the NeuronCheckSystem::Plugin.add_keyword block, like a normal class definition of Ruby, you can define a method. Then, by defining the above-mentioned three methods in which you can define the operation of the keyword.

Keyword registered in the manner described above, it is possible to use in the same way as other keywords in the ndecl block.

module Foo
  extend NeuronCheck
  ndecl {
    args boolean
  def self.foo_func(flag: false)

Foo.foo_func(flag: 'invalid')
#=> script.rb:30:in `<main>': argument `flag' of `Foo.foo_func' must be boolean value, but was "invalid" (NeuronCheckError)
#             got: "invalid"
#       signature: Foo.foo_func(flag:boolean value)
#     declared at: script.rb:22:in `block in <module:Foo>'

Built-in keywords such as respondable, any and except have been defined by using the plug-in mechanism. (However, there is also a place where you are using the method is not described in the above) If you want to see the contents of the implementation, please refer to the source file neuroncheck/builtin_keyword.rb.

It should be noted that, in addition to the NeuronCheckSystem::Plugin.add_keyword, It can also be used two methods below.

require 'neuroncheck'

# As a `boolean` keyword of aliases, define a new `bool` keyword
NeuronCheckSystem::Plugin.alias_keyword(:bool, :boolean)
# To remove a `boolean` keyword previously defined