From: Jonas Galvez <jonasgalvez@...>
Date: 2005-09-28T07:17:39+09:00
Subject: Re: Dynamically generating classes?

Austin Ziegler wrote:
> Object.const_set(name, klass)

Thanks all. Here's what I'm trying to do exactly:

ERROR_CODES = YAML::load open('config/errorcodes.yml').read

for k, v in ERROR_CODES
     Object.const_set(k, Class.new(Exception) {
         def to_s
             "{code: #{v['code']}, message: #{v['message']}}"
         end
     })
end

o = MyException.new # "MyExcetion" is defined in the YAML file
puts o

Unfortunately, this doesn't seem to work:

test.rb:8:in `to_s': undefined local variable or method `v' for 
#<NotAFeed:0x2b6ca08> (NameError)
         from test.rb:14:in `puts'
         from test.rb:14

Here's the equivalent Python code (which works):

ERROR_CODES = syck.load(open('config/errorcodes.yml').read())

for k, v in ERROR_CODES.items():
     nexc = new.classobj(k, (Exception,), {})
     code, message = v
     tostr = lambda self: "{code: %s, message: %s}" % code, message
     setattr(nexc, "__str__", new.instancemethod(tostr, None, nexc))
     globals()[k] = nexc

try:
     raise MyException
except MyException, e:
     print e # prints "{code: ..., message: ...}"


Thanks again.

--Jonas Galvez