An example using "yield self if block_given?"

yield.rb

# No yielding

class NormPerson
  attr_accessor :first, :last
  def initialize(first = nil, last = nil)
    @first = first
    @last = last
  end
  def hello
    puts "#{@first} #{@last} says hello!"
  end
end

# You could do it like this...
ben = NormPerson.new("Ben", "Alman")
ben.hello # Ben Alman says hello!

# Or like this...
ben = NormPerson.new
ben.first = "Ben"
ben.last = "Alman"
ben.hello # Ben Alman says hello!

# (Optional) yielding

class YieldPerson
  attr_accessor :first, :last
  def initialize(first = nil, last = nil)
    @first = first
    @last = last
    yield self if block_given?
  end
  def hello
    puts "#{@first} #{@last} says hello!"
  end
end

# While both of the previous ways work, so does this...
YieldPerson.new do |p|
  p.first = "Ben"
  p.last = "Alman"
  p.hello # Ben Alman says hello!
end

ah, very interesting. so #tap must be implemented along the lines of "yield self if block_given?; self" or something similar

Could you please help me to understand the difference between yield self and yield?

krivek007, I know this is extremelybold but just in case someone else sees this and was curious. The yield self is just a yield(self). It's passing itself as the parameter to the block statement. So when it says YieldPerson.new do |p|, that p is self. Thus it gets translated to

self.first = "Ben"
self.last = "Alman"
self.hello

That last line calls hello on it's self object and you get the output.

This explanation is amazing!! I have been looking for a good explanation for yield self if block_given? , and after I read through this example, I finally truly understand!! Thank you so much