In Ruby, inspect does not substitute to_s

In Python,

class Foo:
  def __repr__(self):
    return 'bar'
foo=Foo()
str(foo) # 'bar'

str(foo) gives 'bar' (both in Py2/Py3). So, if __repr__ is defined and __str__ is not defined, __repr__ is called instead.

However, in Ruby,

class Foo
  def inspect
    'bar'
  end
end
foo=Foo.new
foo.to_s # #<Foo:0x0000....>
p foo # bar
puts foo # #<Foo:0x0000....>

foo.to_s does not give 'bar'. So, if you define inspect, you should also define to_s.

検索用：Rubyではinspectはto_sを代替しない