Weird behavior of case/when

[Nicolas Desprès]

I'm getting a very weird result using case/when.

$ cat test.rb
def test(a)
case a.class
when Class
puts "class"
when String
puts "string"
else
puts "else"
end
end

test(Float)
test("hello")
test(42)
$ ruby test.rb
class
class
class
$ ruby --version
ruby 1.8.4 (2005-12-24) [i686-linux]

I would have exepected the following output:

class
string
else

Does anyone have an explanation about this issue?

Cheers,

--=20
Nicolas Despr=E8s

 

[Kroeger, Simon (ext)]

=20

-----Original Message-----
From: Nicolas Despr=E8s [mailto:[email protected]]=20
Sent: Wednesday, July 12, 2006 10:31 AM
To: ruby-talk ML
Subject: Weird behavior of case/when
=20
I'm getting a very weird result using case/when.
=20
$ cat test.rb
def test(a)
case a.class
when Class
puts "class"
when String
puts "string"
else
puts "else"
end
end
=20
test(Float)
test("hello")
test(42)
$ ruby test.rb
class
class
class
$ ruby --version
ruby 1.8.4 (2005-12-24) [i686-linux]
=20
I would have exepected the following output:
=20
class
string
else
=20
Does anyone have an explanation about this issue?
=20
Cheers,

case uses =3D=3D=3D which is well defined for obj =3D=3D=3D class.=20
What you do is checking the class of a.class which is a class itself.

To make it short: use 'case a' instead of 'case a.class'

cheers

Simon

 

[Pit Capitain]

I'm getting a very weird result using case/when.
(...)

Nicolas, why do you find it weird? Have you read the documentation, for
example

http://phrogz.net/ProgrammingRuby/tut_expressions.html#caseexpressions

Regards,
Pit

 

[Nicolas Desprès]

case uses =3D=3D=3D which is well defined for obj =3D=3D=3D class.
What you do is checking the class of a.class which is a class itself.

To make it short: use 'case a' instead of 'case a.class'

Thank you. I knew that case uses =3D=3D=3D but I would have never expected
that it behaves this way.

Regards,

--=20
Nicolas Despr=E8s