Strange behavior with constants

ruby-talk
1

I have code similar to the snippet below:

···

--

class X
def initialize &b
self.class.class_eval &b
end
end

class Y < X
def initialize &b
super(&b)
end
end

a = Y.new do
CONST = 3
end

puts class Y; CONST; end
puts class X; CONST; end

--

Ideally, calling Y's constructor should create a constant in Y and Y alone,
since self in X#initialize is an instance of Y. However, running this code
yields 3 and 3 - somehow the constant has been declared in X instead of in
Y.

What am I doing wrong?

I've tried other variations on self.class.class_eval, including
self.instance_eval, eval("b.call", binding), all to no avail. Any help would
be appreciated.

--
Bill Atkins

2

Hi,

···

In message "Re: Strange behavior with constants" on Wed, 3 Aug 2005 03:41:42 +0900, Bill Atkins <batkins57@gmail.com> writes:

class X
def initialize &b
self.class.class_eval &b
end
end

class Y < X
def initialize &b
super(&b)
end
end

a = Y.new do
CONST = 3
end

puts class Y; CONST; end
puts class X; CONST; end

Ideally, calling Y's constructor should create a constant in Y and Y alone,
since self in X#initialize is an instance of Y. However, running this code
yields 3 and 3 - somehow the constant has been declared in X instead of in
Y.

What am I doing wrong?

Constant assignment is done in the context determined at compile time,
that means you have defined CONST in the toplevel. Use const_set
method instead.

              matz.