diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Lib/contextlib.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Lib/contextlib.py Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,153 @@ +"""Utilities for with-statement contexts. See PEP 343.""" + +import sys +from functools import wraps + +__all__ = ["contextmanager", "nested", "closing"] + +class GeneratorContextManager(object): + """Helper for @contextmanager decorator.""" + + def __init__(self, gen): + self.gen = gen + + def __enter__(self): + try: + return self.gen.next() + except StopIteration: + raise RuntimeError("generator didn't yield") + + def __exit__(self, type, value, traceback): + if type is None: + try: + self.gen.next() + except StopIteration: + return + else: + raise RuntimeError("generator didn't stop") + else: + if value is None: + # Need to force instantiation so we can reliably + # tell if we get the same exception back + value = type() + try: + self.gen.throw(type, value, traceback) + raise RuntimeError("generator didn't stop after throw()") + except StopIteration, exc: + # Suppress the exception *unless* it's the same exception that + # was passed to throw(). This prevents a StopIteration + # raised inside the "with" statement from being suppressed + return exc is not value + except: + # only re-raise if it's *not* the exception that was + # passed to throw(), because __exit__() must not raise + # an exception unless __exit__() itself failed. But throw() + # has to raise the exception to signal propagation, so this + # fixes the impedance mismatch between the throw() protocol + # and the __exit__() protocol. + # + if sys.exc_info()[1] is not value: + raise + + +def contextmanager(func): + """@contextmanager decorator. + + Typical usage: + + @contextmanager + def some_generator(): + + try: + yield + finally: + + + This makes this: + + with some_generator() as : + + + equivalent to this: + + + try: + = + + finally: + + + """ + @wraps(func) + def helper(*args, **kwds): + return GeneratorContextManager(func(*args, **kwds)) + return helper + + +@contextmanager +def nested(*managers): + """Support multiple context managers in a single with-statement. + + Code like this: + + with nested(A, B, C) as (X, Y, Z): + + + is equivalent to this: + + with A as X: + with B as Y: + with C as Z: + + + """ + exits = [] + vars = [] + exc = (None, None, None) + try: + for mgr in managers: + exit = mgr.__exit__ + enter = mgr.__enter__ + vars.append(enter()) + exits.append(exit) + yield vars + except: + exc = sys.exc_info() + finally: + while exits: + exit = exits.pop() + try: + if exit(*exc): + exc = (None, None, None) + except: + exc = sys.exc_info() + if exc != (None, None, None): + # Don't rely on sys.exc_info() still containing + # the right information. Another exception may + # have been raised and caught by an exit method + raise exc[0], exc[1], exc[2] + + +class closing(object): + """Context to automatically close something at the end of a block. + + Code like this: + + with closing(.open()) as f: + + + is equivalent to this: + + f = .open() + try: + + finally: + f.close() + + """ + def __init__(self, thing): + self.thing = thing + def __enter__(self): + return self.thing + def __exit__(self, *exc_info): + self.thing.close()