Question

我想创建一个类，在初始化此类的Object期间，将为其中一个变量赋值，这样就无法更改。例如：

person = Person.new("Tom")
person.name  #=> Tom
person.name = "Bob"

这应该引发错误或：

person.name #=> Tom -> still

Answer 1

class Person
  def initialize name
    @name = name
  end
  attr_reader :name
end

person = Person.new("Tom")
person.name         #=> Tom
begin
  person.name = "Bob"
rescue
  puts $!.message   # => Undefined method error
end
person.name         #=> Tom

Answer 2

我认为这会对您有所帮助：static variables in ruby

class Foo
 @@foos = 0

 def initialize
 @@foos += 1
 end

 def self.number_of_foos
 @@foos
 end
end

Foo.new
Foo.new
Foo.number_of_foos #=> 2

如何在Ruby中创建变量public final

2 个答案: