Hand over block to a submethod

ruby-talk
1

hi @ all,

lets assume I have two methods in class Func

class Func

  def self.mean(array)
    return 0 if(array.size == 0)
    if(block_given?)
      return array.map{|x| yield(x)}.sum.to_f / array.size
    end
    return array.sum.to_f / array.size
  end

  def self.variance(array)
    return 0 if array.size == 0
    avr = Func.mean(array) #HOW TO HAND OVER A BLOCK???

    if(block_given?)
      return array.map { |i| (yield(i) - avr)**2 }.sum / array.size
    end
    return self.map { |i| (i - avr)**2 }.sum / self.size

  end

end

my problem is, that i have to hand over the block given to variance to
the mean method. is this possible and if yes how?

thanks in advance

greets bernhard

···

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2

1.9.2p290 :001 > def test
1.9.2p290 :002?> if block_given?
1.9.2p290 :003?> puts "I have a block"
1.9.2p290 :004?> yield
1.9.2p290 :005?> else
1.9.2p290 :006 > puts "no block"
1.9.2p290 :007?> end
1.9.2p290 :008?> end
=> nil
1.9.2p290 :011 > def other &blk
1.9.2p290 :012?> puts "passing block"
1.9.2p290 :013?> test &blk
1.9.2p290 :014?> end
=> nil
1.9.2p290 :015 > other
passing block
no block
=> nil
1.9.2p290 :018 > other {puts "I'm the block"}
passing block
I have a block
I'm the block
=> nil

Jesus.

···

On Tue, Sep 11, 2012 at 12:31 PM, bernhard stoecker <lists@ruby-forum.com> wrote:

hi @ all,

lets assume I have two methods in class Func

class Func

  def self.mean(array)
    return 0 if(array.size == 0)
    if(block_given?)
      return array.map{|x| yield(x)}.sum.to_f / array.size
    end
    return array.sum.to_f / array.size
  end

  def self.variance(array)
    return 0 if array.size == 0
    avr = Func.mean(array) #HOW TO HAND OVER A BLOCK???

    if(block_given?)
      return array.map { |i| (yield(i) - avr)**2 }.sum / array.size
    end
    return self.map { |i| (i - avr)**2 }.sum / self.size

  end

end

my problem is, that i have to hand over the block given to variance to
the mean method. is this possible and if yes how?

thanks in advance

greets bernhard

--
Posted via http://www.ruby-forum.com/\.

3

You can reference the block passed to the current method with & and
also use that notation to forward it to another method:

def m1(a,b,c,d, &bl)
  m2(x, y, z, &bl)
end

def m2
  yield 1
end

Kind regards

robert

···

On Tue, Sep 11, 2012 at 12:31 PM, bernhard stoecker <lists@ruby-forum.com> wrote:

my problem is, that i have to hand over the block given to variance to
the mean method. is this possible and if yes how?

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

4

cool! thanks to you guys

···

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