[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.ruby

class variable weirdness

Alex Combas

1/26/2006 3:06:00 AM

I was fooling around with class variables tonight, and I know this is
pretty silly, but forsome reason this code will work when in
its own class, as you can see in class A and class B, but when I
put the code together into class C I get an error

class_vars.rb:26: undefined method `up=' for C:Class (NoMethodError)

Can anyone explain why this is happening?

class A
@@foo=1
def self.foo=(n)
@@foo = n
end
end
#prints "10"
puts "%s" % A.foo=10

class B
@@foo=1
def self.up
@@foo+=1
end
end
#prints "2"
puts "%s" % B.up

class C
@@foo=1
def self.foo=(n)
@@foo = n
end
def self.up
@@foo+=1
end
end
#should print "2, 10" but it doesn't work for me.
puts "%s, %s" % (C.up,C.foo=10)


--
Alex Combas
http://noodlejunkie.blo...
3 Answers

Alex Combas

1/26/2006 4:21:00 AM

0

hi David

On 1/25/06, dblack@wobblini.net <dblack@wobblini.net> wrote:
> > Can anyone explain why this is happening?
> [...]
> > puts "%s, %s" % (C.up,C.foo=10)
>
> You need an array there: [C.up, C.foo=10]. The way you've got it,
> what's happening is that it's being parsed as two assignments:
>
> C.up = 10
> C.foo = nil
>

Thanks I appreciate the quick reply, I think the () was a bit of
python showing its roots.
What I would like to do now is get instances of those classes and use the
methods that I've defined but I cant figure out how, without changing the class.

class A
@@foo=1
def self.foo=(n)
@@foo = n
end
end
puts "%s" % A.foo=10
a = A.new
#this does not work for an instance
#puts "%s" % a.foo=10


--
Alex Combas
http://noodlejunkie.blo...

dblack

1/26/2006 4:35:00 AM

0

Alex Combas

1/26/2006 5:08:00 AM

0

> Instances of A don't have a foo method, so you would indeed have to
> change the class to give them one. Is there a reason you don't want
> to in this particular case?

Yes I see I can not have it both ways now, either a class.method or a
instance.method
but not both with the same declairation.
Thanks David

--
Alex Combas
http://noodlejunkie.blo...