sort_by{rand} doesn't shuffle array

[Pat Maddox]

I did some searching on how to shuffle an array, and found
sort_by{rand}. However, if I call it, it doesn't make a change to my
array at all. I've got a class like this
class MyClass
def initialize
# Populate the array
@my_array =3D Array.new
...
end

def shuffle!
@my_array.sort_by{rand}
end
end

If I call shuffle! from my code, the array's elements are still in the
order that they were created. Why are they not being shuffled like I
want?

 

[Mauricio Fernandez]

def shuffle!
@my_array.sort_by{rand}

@my_array = @my_array.sort_by{rand}

 

[Devin Mullins]

@my_array = @my_array.sort_by{rand}

or @my_array.sort_by! { rand }

 

[Sylvain Joyeux]

or @my_array.sort_by! { rand }
Except that sort_by! does not exist ;-) (at least not in 1.8.4)

 

[Mauricio Fernandez]

or @my_array.sort_by! { rand }

RUBY_RELEASE_DATE # => "2005-12-24"
RUBY_VERSION # => "1.8.4"
%w[a b c d].sort_by!{rand} # =>
# ~> -:3: undefined method `sort_by!' for ["a", "b", "c", "d"]:Array (NoMethodError)