Using a @@class_variable into a Module

Hi, I want to declare a @@class_variable in class A.
Class A includes a Module M and I want some methods in M using the
@@class_variable but I get some problem:


module M
def kk
#puts (eval %{ #{send(‘class’).class_variables[0]} })
puts @@class_var
end
end

class A
include M
@@class_var = “kaka1”
end

a = A.new
a.kk
NameError: uninitialized class variable @@class_var in M
from ./class_attr1.rb:4:in `kk’

I understand the problem. Because the nature of class variables when
the Module M uses @@ it looks into a class variable defined in same
class/module.

Is there any way I could use a class A @class_var into a included M
module methods? If not then I’ll use a normal attribute but I don’t
like it since it’s a constant value that could perfectly be a class
variable instead of initialiting it in each A instance creation.

Thanks a lot.

On Mon, May 19, 2008 at 8:02 PM, Iñaki Baz C. [email protected]
wrote:

end

I understand the problem. Because the nature of class variables when
the Module M uses @@ it looks into a class variable defined in same
class/module.

Is there any way I could use a class A @class_var into a included M
module methods? If not then I’ll use a normal attribute but I don’t
like it since it’s a constant value that could perfectly be a class
variable instead of initialiting it in each A instance creation.

So why not making it a constant? Try to stay away from class
variables, they are evil.

2008/5/20, Iñaki Baz C. [email protected]:

2008/5/20, Michael F. [email protected]:

So why not making it a constant? Try to stay away from class
variables, they are evil.

Nice suggestion, but I’m not sure if that wwill be valid since I need
various clases each one with a own constant value and all of then
including a module that uses that constant. I’ll try it.

Yeah, it works!

module M
def kk
puts self.class::VAR
end
end

class A
include M
VAR = “--------------------- @@ A ---------------------”
end

class B
include M
VAR = “--------------------- @@ B ---------------------”
end

irb> a=A.new
irb> a.kk
“--------------------- @@ A ---------------------”

irb> b=B.new
irb> b.kk
“--------------------- @@ BA ---------------------”

irb> a.kk
“--------------------- @@ A ---------------------”

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