On Thursday, March 10, 2011 at 13:59, kyossi wrote:

Hi,

I'm plan to add some functionality to existing attr_accessor.
I've started with re-implement attr_accessor with same functionality,
but when I implement it by define_method, it failed with Segmentation
fault when I call valueForKey(:key).

Am i doing wrong with class Base2??,

The Code is

#utility
class String
#upcase first char. "foo".upcaseFirstChar => "Foo"
def upcaseFirstChar
self[0].upcase + self[-self.size+1, self.size-1]
end
end

#implement of my_attr_accessor with evaluate string. works fine
class Base
def self.my_attr_accessor(sym)
class_eval %{
def #{sym}
@#{sym}
end

def set#{sym.to_s.upcaseFirstChar}(val)
@#{sym} = val
end
}}
end
end

class MyClass < Base
my_attr_accessor :foo
end


obj = MyClass.new
obj.setFoo(3)
p obj.foo #=>3
p obj.valueForKey(:foo) #=>3

#another implement of my_attr_accessor
class Base2
def self.my_attr_accessor(sym)
define_method(sym) do
instance__variable_get("@#{sym}")
end

define_method("set#{sym.to_s.upcaseFirstChar}") do |val|
instance_variable_set("@#{sym}", val)
end
end
end

class MyClass2 < Base2
my_attr_accessor :foo
end

obj2 = MyClass2.new
obj2.setFoo(7)
p obj2.foo #=>7
p obj2.valueForKey(:foo) #=> Segmentation fault


=====================
$ macruby my_attr_accessor.rb
3
3
7
Segmentation fault
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