Question

我试图使用两个参数 - title和author来定义一个类方法。当我试图传递我的论点时，我得到了一个参数错误

语法错误，意外＆＃39;，＆＃39;，期待＆＃39;）＆＃39; book.set_title_and_author =（＆＃34; Ender的游戏＆＃34;，＆＃34; Orson Scott Card＆＃34;）

class Book

  def set_title_and_author= (title, author)
    @title = title
    @author = author
  end

  def description
    "#{@title}was written by #{@author}"
  end

end

book = Book.new

book.set_title_and_author= ("Ender's Game", "Orson Scott Card)

p book.description

我不允许在我的setter方法中传递多个参数，或者我还缺少其他什么？

Answer 1

您确实无法将多个参数传递给以=结尾的方法。但是，setter方法不需要以=结尾，当然：你可以set_title_and_author(title, author)。

另一种方法是让方法采用数组：

def set_title_and_author= (title_and_author)
    @title, @author = title_and_author
end

#...

book.set_title_and_author= ["Ender's Game", "Orson Scott Card"]

如果您执行后者，从风格上讲，我建议您删除set并调用方法title_and_author=。 set =是多余的。

Answer 2

class Book
  def set_title_and_author(title, author)
    @title = title
    @author = author
  end

  def description
    "#{@title}was written by #{@author}"
  end
end

book = Book.new
book.set_title_and_author("Ender's Game", "Orson Scott Card")
p book.description

但更明确的方法将是

class Book
  attr_accessor :title, :author

  def description
    "#{@title}was written by #{@author}"
  end
end

book = Book.new
book.title = "Ender's Game"
book.author = "Orson Scott Card"
p book.description

最后使用构造函数来设置属性（并避免不必要的可变性）要好得多

book = Book.new("Ender's Game", "Orson Scott Card")

Answer 3

=符号是不必要的。请执行以下操作：

class Book
  def set_title_and_author(title, author)
    @title = title
    @author = author
  end

  def description
    "#{@title} was written by #{@author}"
  end
end
book = Book.new
book.set_title_and_author("Ender's Game","Orson Scott Card")
p book.description

这对我有用。

一次为setter分配多个值：self.x =（y，z）会导致语法错误

3 个答案: