#!/usr/bin/env python
"""
miniclass.py - Coroutine Generators
Authors: tav, sbp
Derived from: 
http://trac.espnow.net/file/sandbox/tav/2weeks/pyutil/coroutine/coroutine.py
http://svn.espnow.net/svnroot/sandbox/tav/2weeks/pyutil/coroutine/coroutine.py
http://irclogs.espnow.net/esp.artifex/2005.02.27.log
License: Public domain
"""

import inspect
from string import Template

minigen = Template("""
def $name$original:
   m = type('Miniclass', (object,), $name.__gen__.__dict__)()
   m.__iter__ = lambda self: self
   m.next = $name.__gen__$replaced.next
   return m
""")

def miniclass(generator):
   name = generator.__name__
   args, varargs, varkw = inspect.getargs(generator.func_code)
   args[0] = 'm'

   original = inspect.formatargspec(args[1:], varargs, varkw)
   replaced = inspect.formatargspec(args, varargs, varkw)

   store = {}
   exec(minigen.substitute(locals()), generator.func_globals, store)

   m = store[name]
   m.__doc__ = generator.__doc__
   m.__gen__ = generator

   return m

@miniclass
def countdown(self, n):
   """Countdown from n to 0.

   Example: 
   >>> c = countdown(10)
   >>> c.next()
   10
   >>> c.next()
   9
   >>> c.next()
   8
   >>> c.n = 3
   >>> c.next()
   2
   >>> c.next()
   1
   """
   self.n = n
   while (self.n > 0): 
      yield self.n
      self.n -= 1

class Debugger(object): 
   def __init__(self, globals, locals): 
      self.globals = globals
      self.locals = locals

   def write(self, code): 
      code = code.rstrip('\r\n')
      if code: 
         print '>>>', code
         try: print eval(code, self.globals, self.locals)
         except SyntaxError: exec(code + '\n', self.globals, self.locals)

debugger = Debugger(globals(), locals())

def test(): 
   print >> debugger, 'c = countdown(10)'
   print >> debugger, 'c.next()'
   print >> debugger, 'c.next()'
   print >> debugger, 'c.next()'
   print >> debugger, 'c.n = 3'
   print >> debugger, 'c.next()'
   print >> debugger, 'c.next()'

def main(): 
   import doctest
   doctest.testmod()

if __name__=="__main__": 
   main()