Class: Algebrick::Protocol

Inherits:

Module

• Object
• Module
• Algebrick::Protocol

show all

Includes:

TypeCheck

Defined in:

lib/algebrick/protocol.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) methods readonly

  Returns the value of attribute methods.

Instance Method Summary (collapse)

• - (Object) implement(klass, &implementation)

  def implement(klass, method = single?, &implementation) Type! method, Symbol klass.send :define_method, method, &implementation end.

• - (Protocol) initialize(*methods) constructor

  A new instance of Protocol.

• - (Boolean) single?
• - (Object) type_error(value)

Methods included from TypeCheck

#Child!, #Child?, #Match!, #Match?, #Type!, #Type?, error

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# File 'lib/algebrick/protocol.rb', line 19

def initialize(*methods)
  @methods = methods
  methods.each do |method|
    define_singleton_method method do |obj, *args, &block|
      Type? obj, self or type_error obj
      obj.send method, *args, &block
    end

    define_method method do |*args, &block|
      raise NotImplementedError
    end
  end

  if single?
    [:call, :[]].each do |name|
      define_singleton_method name do |obj, *args, &block|
        send methods.first, obj, *args, &block
      end
    end
  end
end

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# File 'lib/algebrick/protocol.rb', line 16

def methods
  @methods
end

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# File 'lib/algebrick/protocol.rb', line 50

def implement(klass, &implementation)
  klass.send :include, self
  # TODO check overrides
  klass.class_eval &implementation

  missing = methods - klass.instance_methods
  unless missing.empty?
    raise "missing implementation for #{missing} methods"
  end
end

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# File 'lib/algebrick/protocol.rb', line 41

def single?
  @methods.size == 1 ? @methods.first : nil
end

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# File 'lib/algebrick/protocol.rb', line 61

def type_error(value)
  raise TypeError, "Value (#{value.class}) '#{value}' does not implement #{self} protocol"
end