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Passing a hash to a method ∞

def foo( hash )
  p hash[:a]
  p "yay"
end
foo( { :a=>'testing!' } )

Passing a method name using yield ∞

A simple example:

def example_one
  return "This is example one"
end

def example_two
  return "This is example two"
end

def example_yield()
  puts yield
end

example_yield() { example_one() }
example_yield() { example_two() }

A more complex example ∞

You can also pass a different number of parameters, and deal with them intelligently.

# First you set up a method which can handle a yield:

def yield_method( string, *splat )
  array = string.split( ' ' )
  array.each_index { |i|
    next if i.odd?
    array[i] = yield( array[i], splat )
  }
  return array
end

# Then you set up one or more methods which you'd like to pass to the above method:

def example_method( string, *array )
  if array.size > 0 then
    append = ' ' + array[0..-1].join( ' ' )
  else
    append = ''
  end
  string = "{#{ string }}#{append}"
  return string
end

# You use all of this like so:

p yield_method( "one two three four" ) { |i| example_method( i ) }.join( ' ' )
p yield_method( "one two three four" ) { |i| example_method( i, 'hello' ) }.join( ' ' )