用块初始化对象 [英] Initialize an object with a block

问题描述

是否可以用块初始化一个对象，如下所示?

Is it possible to initialize an object with a block as follows?

class Foo
  attr_reader :bar,:baz
  def initialize(bar,baz)
    @bar, @baz = bar, baz
  end
end

Foo.new do |bar, baz|
  # some logic to be implemented
  # @bar, @baz to be assigned
end

推荐答案

当然，你可以在 initialize 中yield，没什么特别的:

Of course, you can yield from within initialize, there's nothing special about it:

class Foo
  attr_accessor :bar, :baz
  def initialize
    yield self
  end
end

Foo.new do |f|
  f.bar = 123
  f.baz = 456
end
#=> <Foo:0x007fed8287b3c0 @bar=123, @baz=456>

您还可以使用 instance_eval:

You could also evaluate the block in the context of the receiver using instance_eval:

class Foo
  attr_accessor :bar, :baz
  def initialize(&block)
    instance_eval(&block)
  end
end

Foo.new do
  @bar = 123
  @baz = 456
end
#=> #<Foo:0x007fdd0b1ef4c0 @bar=123, @baz=456>

这篇关于用块初始化对象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！