wrw/dispatch.py

   1 import sys, traceback
   2 import env
   3
   4 __all__ = ["restart"]
   5
   6 class restart(Exception):
   7     def handle(self, req):
   8         pass
   9
  10 def mangle(result):
  11     try:
  12         iter(result)
  13     except TypeError:
  14         pass
  15     else:
  16         return result
  17     return [str(result)]
  18
  19 class iterproxy(object):
  20     # Makes sure iter(real).next() is called immediately, in order to
  21     # let generator code run.
  22     def __init__(self, real):
  23         self.bk = real
  24         self.bki = iter(real)
  25         self._next = [None]
  26         self.next()
  27
  28     def __iter__(self):
  29         return self
  30
  31     def next(self):
  32         if self._next is None:
  33             raise StopIteration()
  34         ret = self._next[0]
  35         try:
  36             self._next[:] = [self.bki.next()]
  37         except StopIteration:
  38             self._next = None
  39         return ret
  40
  41     def close(self):
  42         if hasattr(self.bk, "close"):
  43             self.bk.close()
  44
  45 def defaulterror(req, excinfo):
  46     import resp
  47     traceback.print_exception(*excinfo)
  48     raise resp.httperror(500)
  49
  50 def wraphandler(handler, excinfo):
  51     def wrapped(req):
  52         return handler(req, excinfo)
  53     return wrapped
  54
  55 errorhandler = env.var(defaulterror)
  56
  57 def handle(req, startreq, handler):
  58     eh = errorhandler.val
  59     try:
  60         resp = [""]
  61         while True:
  62             try:
  63                 resp = iterproxy(handler(req))
  64                 break
  65             except restart, i:
  66                 handler = i.handle
  67             except Exception, i:
  68                 if eh is None:
  69                     raise
  70                 handler = wraphandler(eh, sys.exc_info())
  71                 eh = None
  72         req.commit(startreq)
  73         return resp
  74     finally:
  75         req.cleanup()