Behavior of different conversion operators provided by Kernel

conversions.rb

values = [nil, '', [], {}, true, false, 0, 3.51, '0', '42', '0xb', '1.2', '1e2',
  'nil', 'true', 'false' ,'foo', [3,4], {5=>6}]
converters = %w(String to_s Integer to_i Float to_f Array to_a)

table_format = "%9s" * converters.size + "\n"
printf( "%9s ", '')
legend = converters
printf(table_format, *legend)

values.each do |v|
  printf "%9s:", v.inspect
  results = converters.map do |cvt|
    begin
      if cvt =~ /to.*/
        v.send(cvt).inspect
      else
        send(cvt, v).inspect
      end
    rescue => e
      e.class.to_s.sub(/Error$/, '')
    end
  end
  printf(table_format, *results)
end


# Results in:
#ruby 1.8.7 (2011-02-18 patchlevel 334) [i386-mingw32]
#
#             String     to_s  Integer     to_i    Float     to_f    Array     to_a
#      nil:       ""       ""        0        0     Type      0.0       []       []
#       "":       ""       "" Argument        0 Argument      0.0       []       []
#       []:       ""       ""     Type NoMethod     Type NoMethod       []       []
#       {}:       ""       ""     Type NoMethod     Type NoMethod       []       []
#     true:   "true"   "true"     Type NoMethod     Type NoMethod   [true]   [true]
#    false:  "false"  "false"     Type NoMethod     Type NoMethod  [false]  [false]
#        0:      "0"      "0"        0        0      0.0      0.0      [0]      [0]
#     3.51:   "3.51"   "3.51"        3        3     3.51     3.51   [3.51]   [3.51]
#      "0":      "0"      "0"        0        0      0.0      0.0    ["0"]    ["0"]
#     "42":     "42"     "42"       42       42     42.0     42.0   ["42"]   ["42"]
#    "0xb":    "0xb"    "0xb"       11        0 Argument      0.0  ["0xb"]  ["0xb"]
#    "1.2":    "1.2"    "1.2" Argument        1      1.2      1.2  ["1.2"]  ["1.2"]
#    "1e2":    "1e2"    "1e2" Argument        1    100.0    100.0  ["1e2"]  ["1e2"]
#    "nil":    "nil"    "nil" Argument        0 Argument      0.0  ["nil"]  ["nil"]
#   "true":   "true"   "true" Argument        0 Argument      0.0 ["true"] ["true"]
#  "false":  "false"  "false" Argument        0 Argument      0.0["false"]["false"]
#    "foo":    "foo"    "foo" Argument        0 Argument      0.0  ["foo"]  ["foo"]
#   [3, 4]:     "34"     "34"     Type NoMethod     Type NoMethod   [3, 4]   [3, 4]
#   {5=>6}:     "56"     "56"     Type NoMethod     Type NoMethod [[5, 6]] [[5, 6]]
#
#ruby 1.9.2p180 (2011-02-18) [i386-mingw32]
#
#             String     to_s  Integer     to_i    Float     to_f    Array     to_a
#      nil:       ""       ""     Type        0     Type      0.0       []       []
#       "":       ""       "" Argument        0 Argument      0.0     [""] NoMethod
#       []:     "[]"     "[]"     Type NoMethod     Type NoMethod       []       []
#       {}:     "{}"     "{}"     Type NoMethod     Type NoMethod       []       []
#     true:   "true"   "true"     Type NoMethod     Type NoMethod   [true] NoMethod
#    false:  "false"  "false"     Type NoMethod     Type NoMethod  [false] NoMethod
#        0:      "0"      "0"        0        0      0.0      0.0      [0] NoMethod
#     3.51:   "3.51"   "3.51"        3        3     3.51     3.51   [3.51] NoMethod
#      "0":      "0"      "0"        0        0      0.0      0.0    ["0"] NoMethod
#     "42":     "42"     "42"       42       42     42.0     42.0   ["42"] NoMethod
#    "0xb":    "0xb"    "0xb"       11        0     11.0      0.0  ["0xb"] NoMethod
#    "1.2":    "1.2"    "1.2" Argument        1      1.2      1.2  ["1.2"] NoMethod
#    "1e2":    "1e2"    "1e2" Argument        1    100.0    100.0  ["1e2"] NoMethod
#    "nil":    "nil"    "nil" Argument        0 Argument      0.0  ["nil"] NoMethod
#   "true":   "true"   "true" Argument        0 Argument      0.0 ["true"] NoMethod
#  "false":  "false"  "false" Argument        0 Argument      0.0["false"] NoMethod
#    "foo":    "foo"    "foo" Argument        0 Argument      0.0  ["foo"] NoMethod
#   [3, 4]: "[3, 4]" "[3, 4]"     Type NoMethod     Type NoMethod   [3, 4]   [3, 4]
#   {5=>6}: "{5=>6}" "{5=>6}"     Type NoMethod     Type NoMethod [[5, 6]] [[5, 6]]
#