Hi Carlo, On Sep 5, 2009, at 7:27 AM, Carlo Cabanilla wrote:
Hi,
I'm Carlo, I'm new to MacRuby and I'd like to contribute if possible. I found this weird bug when requiring modules that define classes that extend Forwardable and define delgates:
$ echo "require 'csv'; puts 'good'" | macirb require 'csv'; puts 'good' NameError: undefined local variable or method `str' for CSV::Row:Class from 0:in `def_delegator:'
But requiring it from a script works fine:
$ macruby -e "require 'csv'; puts 'good'" good
Same behavior for rss/parser:
$ echo "require 'rss/parser'; puts 'good'" | macirb require 'rss/parser'; puts 'good' NameError: undefined local variable or method `str' for RSS::Parser:Class from 0:in `def_delegator:'
$ macruby -e "require 'rss/parser'; puts 'good'" good
I traced it to the def_instance_delegator method in Forwardable:
def def_instance_delegator(accessor, method, ali = method) str = %Q{ def #{ali}(*args, &block) #{accessor}.send(:#{method}, *args, &block) end }
# If it's not a class or module, it's an instance begin module_eval(str) rescue instance_eval(str) end end
I found that if I just hard code the str value as the parameters to module_eval and instance_eval, it works:
def def_instance_delegator(accessor, method, ali = method) # If it's not a class or module, it's an instance begin module_eval(%Q{ def #{ali}(*args, &block) #{accessor}.send(:#{method}, *args, &block) end }) rescue instance_eval(%Q{ def #{ali}(*args, &block) #{accessor}.send(:#{method}, *args, &block) end }) end end
This is kind of hack, so I'm assuming the root cause has to do with how macirb treats variable scope? Is this a known bug? Can I help somehow?
I think this is the same bug that has been reported a few times on trac. Currently eval with Binding has a problem with method-scoped local variables. This is on the top of our TODO list right now, if you want to help you need to discover why MacRuby wrongly compiles local variables in this very specific case. The compiler is compiler.cpp. Let me know if you find anything interesting or if you have any question! Laurent