Passing blocks and such

ruby-talk
1

i was just playing around with some ideas and came across something i could
not do although it seems to me that it wouldn’t be unreasonable to want to do
so:

def a_block_like_method(i)
	puts i
end

arr = [1, 2, 3]
arr.each do a_block_like_method(i)

i also tried

def pass_a_block
	{ |i| puts i }
end

arr = [1, 2, 3]
arr.each do pass_a_block

and i tried a few other variations with no success. is there a way to pass a
block or use a method as a block?

···

–
tom sawyer, aka transami
transami@transami.net

2

Tom Sawyer wrote:

i was just playing around with some ideas and came across something i could
not do although it seems to me that it wouldn’t be unreasonable to want to do
so:

def a_block_like_method(i)
puts i
end

arr = [1, 2, 3]
arr.each do a_block_like_method(i)

Try this:

     arr.each &(method :a_block_like_method)
3

This looks very similar:

  def pass_a_block
    proc { |i| puts i }
  end

  arr = [1, 2, 3]
  arr.each &pass_a_block

But that's probably not what you want. It's not the method, it's a Proc
object (which happens to be the returned object from the method) that's
being iterated. You can use a local variable instead of a method:

  pass_a_block = proc { |i| puts i }

  arr = [1, 2, 3]
  arr.each &pass_a_block

B.

···

On Tue, Feb 18, 2003 at 06:59:48AM +0900, Tom Sawyer wrote:

i also tried

  def pass_a_block
    { |i| puts i }
  end

  arr = [1, 2, 3]
  arr.each do pass_a_block

4

These are the alternatives as far as I can see (plus combinations):

irb(main):001:0> def a_block_like_method(i)
irb(main):002:1> puts i
irb(main):003:1> end
nil
irb(main):004:0> arr = [1, 2, 3]
[1, 2, 3]
irb(main):005:0> arr.each do |i| a_block_like_method(i) end
1
2
3
[1, 2, 3]
irb(main):006:0> block = Proc.new {|i| puts i}
#Proc:0x2ab73f0
irb(main):007:0> arr.each do |i| block.call(i) end
1
2
3
[1, 2, 3]
irb(main):008:0> arr.each &block
1
2
3
[1, 2, 3]
irb(main):009:0>

Why isn’t this sufficient?

Regards

robert

“Tom Sawyer” transami@transami.net schrieb im Newsbeitrag
news:200302171516.53178.transami@transami.net…

i was just playing around with some ideas and came across something i
could
not do although it seems to me that it wouldn’t be unreasonable to want
to do
so:

def a_block_like_method(i)
puts i
end

arr = [1, 2, 3]
arr.each do a_block_like_method(i)

i also tried

def pass_a_block
{ |i| puts i }
end

arr = [1, 2, 3]
arr.each do pass_a_block

and i tried a few other variations with no success. is there a way to
pass a

···

block or use a method as a block?

–
tom sawyer, aka transami
transami@transami.net