在Ruby中使用不同的参数和默认值初始化Class的最有效方法是什么? [英] What is the most efficient way to initialize a Class in Ruby with different parameters and default values?

问题描述

我想要一个类和一些属性，您可以在初始化期间设置它们或使用其默认值.

I would like to have a class and some attributes which you can either set during initialization or use its default value.

class Fruit
  attr_accessor :color, :type
  def initialize(color, type)
    @color=color ||= 'green'
    @type=type ||='pear'
  end
end

apple=Fruit.new(red, apple)

推荐答案

解决此问题的典型方法是使用具有默认值的哈希.如果哈希是方法的最后一个参数，则Ruby具有用于传递哈希值的漂亮语法.

The typical way to solve this problem is with a hash that has a default value. Ruby has a nice syntax for passing hash values, if the hash is the last parameter to a method.

class Fruit
  attr_accessor :color, :type

  def initialize(params = {})
    @color = params.fetch(:color, 'green')
    @type = params.fetch(:type, 'pear')
  end

  def to_s
    "#{color} #{type}"
  end
end

puts(Fruit.new)                                    # prints: green pear
puts(Fruit.new(:color => 'red', :type => 'grape')) # prints: red grape
puts(Fruit.new(:type => 'pomegranate')) # prints: green pomegranate

这里是一个很好的概述: http://deepfall. blogspot.com/2008/08/named-parameters-in-ruby.html

A good overview is here: http://deepfall.blogspot.com/2008/08/named-parameters-in-ruby.html

这篇关于在Ruby中使用不同的参数和默认值初始化Class的最有效方法是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！