On Fri, 14 Jul 2006, Sean O’Halpin wrote:
Hmmm. I’m still getting “singleton method called for a different
object (TypeError)” for this (ruby 1.8.4 (2005-12-24) [i386-mswin32]).
me too.
harp:~ > cat a.rb
class X # role of IO
class << self
def x(*args,&block) # role of open
block.call(1764) if block
end
end
end
OLD = X.method :x
class Y < X # role of File
class << self
def x; “rubbish”; end
end
end
class Y
class << self
define_method(:x, OLD )
end
end
Y.x{|a| puts a }
harp:~ > ruby a.rb
a.rb:23:in `x’: singleton method called for a different object
(TypeError)
from a.rb:23
harp:~ > ruby -v && cat /etc/redhat-release && uname -srm
ruby 1.8.4 (2005-12-01) [i686-linux]
Red Hat Enterprise Linux WS release 3 (Taroon Update 7)
Linux 2.4.21-40.EL i686
you robert?
btw. this challenge was not arbitrary: the increase in metaprogramming
popularity means people are doing things like
def class_method
alias ‘instance_method’, ‘instance_method’ # push
define_method 'instance_method' do
# ...
__instance_method__ 42
# ...
end
ensure
alias ‘instance_method’, ‘instance_method’ # pop
end
but this is neither thread safe (easy to fix) or re-entrant (not easy to
fix).
what i mean is doing
class_method{
class_method{
}
}
blows up.
to avoid this i wanted to develop this pattern
def class_method
instance_method = method ‘instance_method’ # push
define_method 'instance_method' do
# ...
__instance_method__.call 42
# ...
end
ensure
define_method ‘instance_method’, instance_method # pop
end
but, of course, we are seeing that it doesn’t work.
regards.
-a
