gistfile1.txt

y$ cat pass-by-ref.rb 

def pbr_int(i)
   i = 5
end

def pbr_str(s)
   s = "another value"
end

def pbr_list(l)
   l << 5
end

def pbr_hash(h)
   h['a'] = 'bar'
end

puts "== int =="
i = 2
pbr_int(i)
puts "i = #{i}"

puts "== str =="
s = "string value"
pbr_str(s)
puts "s = #{s}"

puts "== hash =="
h = {}
h['a'] = 'foo'
pbr_hash(h)
puts "h = #{h.inspect}"

puts "== list =="
l = []
l << 1
pbr_list(l)
puts "l = #{l.inspect}"

==================================
$ ruby $_
== int ==
i = 2
== str ==
s = string value
== hash ==
h = {"a"=>"bar"}
== list ==
l = [1, 5]