Hand over block to a submethod

Ruby
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 array.map { |i| (i - avr)**2 }.sum / array.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

2

On Tue, Sep 11, 2012 at 12:31 PM, bernhard stoecker
[email protected] wrote:

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

thanks in advance

greets bernhard

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

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.

3

On Tue, Sep 11, 2012 at 12:31 PM, bernhard stoecker
[email protected] 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?

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

4

cool! thanks to you guys