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Updates to the with-statement: 

- New semantics for __exit__() -- it must re-raise the exception
  if type is not None; the with-statement itself doesn't do this.
  (See the updated PEP for motivation.)

- Added context managers to:
  - file
  - thread.LockType
  - threading.{Lock,RLock,Condition,Semaphore,BoundedSemaphore}
  - decimal.Context

- Added contextlib.py, which defines @contextmanager, nested(), closing().

- Unit tests all around; bot no docs yet.
This commit is contained in:
Guido van Rossum 2006-02-28 21:57:43 +00:00
parent 87a8b4fee5
commit 1a5e21e033
12 changed files with 609 additions and 96 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

138
Lib/contextlib.py Normal file
View File

@ -0,0 +1,138 @@
"""Utilities for with-statement contexts. See PEP 343."""
import sys
__all__ = ["contextmanager", "nested", "closing"]
class GeneratorContextManager(object):
"""Helper for @contextmanager decorator."""
def __init__(self, gen):
self.gen = gen
def __context__(self):
return self
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:
try:
self.gen.throw(type, value, traceback)
except StopIteration:
pass
def contextmanager(func):
"""@contextmanager decorator.
Typical usage:
@contextmanager
def some_generator(<arguments>):
<setup>
try:
yield <value>
finally:
<cleanup>
This makes this:
with some_generator(<arguments>) as <variable>:
<body>
equivalent to this:
<setup>
try:
<variable> = <value>
<body>
finally:
<cleanup>
"""
def helper(*args, **kwds):
return GeneratorContextManager(func(*args, **kwds))
try:
helper.__name__ = func.__name__
helper.__doc__ = func.__doc__
except:
pass
return helper
@contextmanager
def nested(*contexts):
"""Support multiple context managers in a single with-statement.
Code like this:
with nested(A, B, C) as (X, Y, Z):
<body>
is equivalent to this:
with A as X:
with B as Y:
with C as Z:
<body>
"""
exits = []
vars = []
exc = (None, None, None)
try:
try:
for context in contexts:
mgr = context.__context__()
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:
exit(*exc)
except:
exc = sys.exc_info()
if exc != (None, None, None):
raise
@contextmanager
def closing(thing):
"""Context manager to automatically close something at the end of a block.
Code like this:
with closing(<module>.open(<arguments>)) as f:
<block>
is equivalent to this:
f = <module>.open(<arguments>)
try:
<block>
finally:
f.close()
"""
try:
yield thing
finally:
thing.close()

29
Lib/decimal.py
View File

@ -2173,6 +2173,32 @@ for name in rounding_functions:
del name, val, globalname, rounding_functions del name, val, globalname, rounding_functions
class ContextManager(object):
"""Helper class to simplify Context management.
Sample usage:
with decimal.ExtendedContext:
s = ...
return +s # Convert result to normal precision
with decimal.getcontext() as ctx:
ctx.prec += 2
s = ...
return +s
"""
def __init__(self, new_context):
self.new_context = new_context
def __enter__(self):
self.saved_context = getcontext()
setcontext(self.new_context)
return self.new_context
def __exit__(self, t, v, tb):
setcontext(self.saved_context)
if t is not None:
raise t, v, tb
class Context(object): class Context(object):
"""Contains the context for a Decimal instance. """Contains the context for a Decimal instance.
@ -2224,6 +2250,9 @@ class Context(object):
s.append('traps=[' + ', '.join([t.__name__ for t, v in self.traps.items() if v]) + ']') s.append('traps=[' + ', '.join([t.__name__ for t, v in self.traps.items() if v]) + ']')
return ', '.join(s) + ')' return ', '.join(s) + ')'
def __context__(self):
return ContextManager(self.copy())
def clear_flags(self): def clear_flags(self):
"""Reset all flags to zero""" """Reset all flags to zero"""
for flag in self.flags: for flag in self.flags:

33
Lib/test/contextmanager.py
View File

@ -1,33 +0,0 @@
class GeneratorContextManager(object):
def __init__(self, gen):
self.gen = gen
def __context__(self):
return self
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:
try:
self.gen.throw(type, value, traceback)
except (type, StopIteration):
return
else:
raise RuntimeError("generator caught exception")
def contextmanager(func):
def helper(*args, **kwds):
return GeneratorContextManager(func(*args, **kwds))
return helper

40
Lib/test/nested.py
View File

@ -1,40 +0,0 @@
import sys
from collections import deque
class nested(object):
def __init__(self, *contexts):
self.contexts = contexts
self.entered = None
def __context__(self):
return self
def __enter__(self):
if self.entered is not None:
raise RuntimeError("Context is not reentrant")
self.entered = deque()
vars = []
try:
for context in self.contexts:
mgr = context.__context__()
vars.append(mgr.__enter__())
self.entered.appendleft(mgr)
except:
self.__exit__(*sys.exc_info())
raise
return vars
def __exit__(self, *exc_info):
# Behave like nested with statements
# first in, last out
# New exceptions override old ones
ex = exc_info
for mgr in self.entered:
try:
mgr.__exit__(*ex)
except:
ex = sys.exc_info()
self.entered = None
if ex is not exc_info:
raise ex[0], ex[1], ex[2]

240
Lib/test/test_contextlib.py Normal file
View File

@ -0,0 +1,240 @@
"""Unit tests for contextlib.py, and other context managers."""
from __future__ import with_statement
import os
import decimal
import tempfile
import unittest
import threading
from contextlib import * # Tests __all__
class ContextManagerTestCase(unittest.TestCase):
def test_contextmanager_plain(self):
state = []
@contextmanager
def woohoo():
state.append(1)
yield 42
state.append(999)
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_finally(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
finally:
state.append(999)
try:
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError()
except ZeroDivisionError:
pass
else:
self.fail("Expected ZeroDivisionError")
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_except(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
except ZeroDivisionError, e:
state.append(e.args[0])
self.assertEqual(state, [1, 42, 999])
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError(999)
self.assertEqual(state, [1, 42, 999])
class NestedTestCase(unittest.TestCase):
# XXX This needs more work
def test_nested(self):
@contextmanager
def a():
yield 1
@contextmanager
def b():
yield 2
@contextmanager
def c():
yield 3
with nested(a(), b(), c()) as (x, y, z):
self.assertEqual(x, 1)
self.assertEqual(y, 2)
self.assertEqual(z, 3)
def test_nested_cleanup(self):
state = []
@contextmanager
def a():
state.append(1)
try:
yield 2
finally:
state.append(3)
@contextmanager
def b():
state.append(4)
try:
yield 5
finally:
state.append(6)
try:
with nested(a(), b()) as (x, y):
state.append(x)
state.append(y)
1/0
except ZeroDivisionError:
self.assertEqual(state, [1, 4, 2, 5, 6, 3])
else:
self.fail("Didn't raise ZeroDivisionError")
class ClosingTestCase(unittest.TestCase):
# XXX This needs more work
def test_closing(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
with closing(x) as y:
self.assertEqual(x, y)
self.assertEqual(state, [1])
def test_closing_error(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
try:
with closing(x) as y:
self.assertEqual(x, y)
1/0
except ZeroDivisionError:
self.assertEqual(state, [1])
else:
self.fail("Didn't raise ZeroDivisionError")
class FileContextTestCase(unittest.TestCase):
def testWithOpen(self):
tfn = tempfile.mktemp()
try:
f = None
with open(tfn, "w") as f:
self.failIf(f.closed)
f.write("Booh\n")
self.failUnless(f.closed)
f = None
try:
with open(tfn, "r") as f:
self.failIf(f.closed)
self.assertEqual(f.read(), "Booh\n")
1/0
except ZeroDivisionError:
self.failUnless(f.closed)
else:
self.fail("Didn't raise ZeroDivisionError")
finally:
try:
os.remove(tfn)
except os.error:
pass
class LockContextTestCase(unittest.TestCase):
def boilerPlate(self, lock, locked):
self.failIf(locked())
with lock:
self.failUnless(locked())
self.failIf(locked())
try:
with lock:
self.failUnless(locked())
1/0
except ZeroDivisionError:
self.failIf(locked())
else:
self.fail("Didn't raise ZeroDivisionError")
def testWithLock(self):
lock = threading.Lock()
self.boilerPlate(lock, lock.locked)
def testWithRLock(self):
lock = threading.RLock()
self.boilerPlate(lock, lock._is_owned)
def testWithCondition(self):
lock = threading.Condition()
def locked():
return lock._is_owned()
self.boilerPlate(lock, locked)
def testWithSemaphore(self):
lock = threading.Semaphore()
def locked():
if lock.acquire(False):
lock.release()
return False
else:
return True
self.boilerPlate(lock, locked)
def testWithBoundedSemaphore(self):
lock = threading.BoundedSemaphore()
def locked():
if lock.acquire(False):
lock.release()
return False
else:
return True
self.boilerPlate(lock, locked)
class DecimalContextTestCase(unittest.TestCase):
# XXX Somebody should write more thorough tests for this
def testBasic(self):
ctx = decimal.getcontext()
ctx.prec = save_prec = decimal.ExtendedContext.prec + 5
with decimal.ExtendedContext:
self.assertEqual(decimal.getcontext().prec,
decimal.ExtendedContext.prec)
self.assertEqual(decimal.getcontext().prec, save_prec)
try:
with decimal.ExtendedContext:
self.assertEqual(decimal.getcontext().prec,
decimal.ExtendedContext.prec)
1/0
except ZeroDivisionError:
self.assertEqual(decimal.getcontext().prec, save_prec)
else:
self.fail("Didn't raise ZeroDivisionError")
if __name__ == "__main__":
unittest.main()

84
Lib/test/test_with.py
View File

@ -7,9 +7,10 @@ from __future__ import with_statement
__author__ = "Mike Bland" __author__ = "Mike Bland"
__email__ = "mbland at acm dot org" __email__ = "mbland at acm dot org"
import sys
import unittest import unittest
from test.contextmanager import GeneratorContextManager from collections import deque
from test.nested import nested from contextlib import GeneratorContextManager, contextmanager
from test.test_support import run_unittest from test.test_support import run_unittest
@ -57,9 +58,48 @@ def mock_contextmanager_generator():
mock.stopped = True mock.stopped = True
class MockNested(nested): class Nested(object):
def __init__(self, *contexts): def __init__(self, *contexts):
nested.__init__(self, *contexts) self.contexts = contexts
self.entered = None
def __context__(self):
return self
def __enter__(self):
if self.entered is not None:
raise RuntimeError("Context is not reentrant")
self.entered = deque()
vars = []
try:
for context in self.contexts:
mgr = context.__context__()
vars.append(mgr.__enter__())
self.entered.appendleft(mgr)
except:
self.__exit__(*sys.exc_info())
raise
return vars
def __exit__(self, *exc_info):
# Behave like nested with statements
# first in, last out
# New exceptions override old ones
ex = exc_info
for mgr in self.entered:
try:
mgr.__exit__(*ex)
except:
ex = sys.exc_info()
self.entered = None
if ex is not exc_info:
raise ex[0], ex[1], ex[2]
class MockNested(Nested):
def __init__(self, *contexts):
Nested.__init__(self, *contexts)
self.context_called = False self.context_called = False
self.enter_called = False self.enter_called = False
self.exit_called = False self.exit_called = False
@ -67,16 +107,16 @@ class MockNested(nested):
def __context__(self): def __context__(self):
self.context_called = True self.context_called = True
return nested.__context__(self) return Nested.__context__(self)
def __enter__(self): def __enter__(self):
self.enter_called = True self.enter_called = True
return nested.__enter__(self) return Nested.__enter__(self)
def __exit__(self, *exc_info): def __exit__(self, *exc_info):
self.exit_called = True self.exit_called = True
self.exit_args = exc_info self.exit_args = exc_info
return nested.__exit__(self, *exc_info) return Nested.__exit__(self, *exc_info)
class FailureTestCase(unittest.TestCase): class FailureTestCase(unittest.TestCase):
@ -294,7 +334,7 @@ class NonexceptionalTestCase(unittest.TestCase, ContextmanagerAssertionMixin):
class NestedNonexceptionalTestCase(unittest.TestCase, class NestedNonexceptionalTestCase(unittest.TestCase,
ContextmanagerAssertionMixin): ContextmanagerAssertionMixin):
def testSingleArgInlineGeneratorSyntax(self): def testSingleArgInlineGeneratorSyntax(self):
with nested(mock_contextmanager_generator()): with Nested(mock_contextmanager_generator()):
pass pass
def testSingleArgUnbound(self): def testSingleArgUnbound(self):
@ -310,7 +350,7 @@ class NestedNonexceptionalTestCase(unittest.TestCase,
m = mock_contextmanager_generator() m = mock_contextmanager_generator()
# This will bind all the arguments to nested() into a single list # This will bind all the arguments to nested() into a single list
# assigned to foo. # assigned to foo.
with nested(m) as foo: with Nested(m) as foo:
self.assertInWithManagerInvariants(m) self.assertInWithManagerInvariants(m)
self.assertAfterWithManagerInvariantsNoError(m) self.assertAfterWithManagerInvariantsNoError(m)
@ -318,14 +358,13 @@ class NestedNonexceptionalTestCase(unittest.TestCase,
m = mock_contextmanager_generator() m = mock_contextmanager_generator()
# This will bind all the arguments to nested() into a single list # This will bind all the arguments to nested() into a single list
# assigned to foo. # assigned to foo.
# FIXME: what should this do: with nested(m) as (foo,): with Nested(m) as (foo):
with nested(m) as (foo):
self.assertInWithManagerInvariants(m) self.assertInWithManagerInvariants(m)
self.assertAfterWithManagerInvariantsNoError(m) self.assertAfterWithManagerInvariantsNoError(m)
def testSingleArgBoundToMultipleElementTupleError(self): def testSingleArgBoundToMultipleElementTupleError(self):
def shouldThrowValueError(): def shouldThrowValueError():
with nested(mock_contextmanager_generator()) as (foo, bar): with Nested(mock_contextmanager_generator()) as (foo, bar):
pass pass
self.assertRaises(ValueError, shouldThrowValueError) self.assertRaises(ValueError, shouldThrowValueError)
@ -535,7 +574,9 @@ class AssignmentTargetTestCase(unittest.TestCase):
class C: class C:
def __context__(self): return self def __context__(self): return self
def __enter__(self): return 1, 2, 3 def __enter__(self): return 1, 2, 3
def __exit__(self, *a): pass def __exit__(self, t, v, tb):
if t is not None:
raise t, v, tb
targets = {1: [0, 1, 2]} targets = {1: [0, 1, 2]}
with C() as (targets[1][0], targets[1][1], targets[1][2]): with C() as (targets[1][0], targets[1][1], targets[1][2]):
self.assertEqual(targets, {1: [1, 2, 3]}) self.assertEqual(targets, {1: [1, 2, 3]})
@ -551,11 +592,26 @@ class AssignmentTargetTestCase(unittest.TestCase):
self.assertEqual(blah.three, 3) self.assertEqual(blah.three, 3)
class ExitSwallowsExceptionTestCase(unittest.TestCase):
def testExitSwallowsException(self):
class AfricanOrEuropean:
def __context__(self): return self
def __enter__(self): pass
def __exit__(self, t, v, tb): pass
try:
with AfricanOrEuropean():
1/0
except ZeroDivisionError:
self.fail("ZeroDivisionError should have been swallowed")
def test_main(): def test_main():
run_unittest(FailureTestCase, NonexceptionalTestCase, run_unittest(FailureTestCase, NonexceptionalTestCase,
NestedNonexceptionalTestCase, ExceptionalTestCase, NestedNonexceptionalTestCase, ExceptionalTestCase,
NonLocalFlowControlTestCase, NonLocalFlowControlTestCase,
AssignmentTargetTestCase) AssignmentTargetTestCase,
ExitSwallowsExceptionTestCase)
if __name__ == '__main__': if __name__ == '__main__':

29
Lib/threading.py
View File

@ -90,6 +90,9 @@ class _RLock(_Verbose):
self.__owner and self.__owner.getName(), self.__owner and self.__owner.getName(),
self.__count) self.__count)
def __context__(self):
return self
def acquire(self, blocking=1): def acquire(self, blocking=1):
me = currentThread() me = currentThread()
if self.__owner is me: if self.__owner is me:
@ -108,6 +111,8 @@ class _RLock(_Verbose):
self._note("%s.acquire(%s): failure", self, blocking) self._note("%s.acquire(%s): failure", self, blocking)
return rc return rc
__enter__ = acquire
def release(self): def release(self):
me = currentThread() me = currentThread()
assert self.__owner is me, "release() of un-acquire()d lock" assert self.__owner is me, "release() of un-acquire()d lock"
@ -121,6 +126,11 @@ class _RLock(_Verbose):
if __debug__: if __debug__:
self._note("%s.release(): non-final release", self) self._note("%s.release(): non-final release", self)
def __exit__(self, t, v, tb):
self.release()
if t is not None:
raise t, v, tb
# Internal methods used by condition variables # Internal methods used by condition variables
def _acquire_restore(self, (count, owner)): def _acquire_restore(self, (count, owner)):
@ -156,6 +166,7 @@ class _Condition(_Verbose):
self.__lock = lock self.__lock = lock
# Export the lock's acquire() and release() methods # Export the lock's acquire() and release() methods
self.acquire = lock.acquire self.acquire = lock.acquire
self.__enter__ = self.acquire
self.release = lock.release self.release = lock.release
# If the lock defines _release_save() and/or _acquire_restore(), # If the lock defines _release_save() and/or _acquire_restore(),
# these override the default implementations (which just call # these override the default implementations (which just call
@ -174,6 +185,14 @@ class _Condition(_Verbose):
pass pass
self.__waiters = [] self.__waiters = []
def __context__(self):
return self
def __exit__(self, t, v, tb):
self.release()
if t is not None:
raise t, v, tb
def __repr__(self): def __repr__(self):
return "<Condition(%s, %d)>" % (self.__lock, len(self.__waiters)) return "<Condition(%s, %d)>" % (self.__lock, len(self.__waiters))
@ -267,6 +286,9 @@ class _Semaphore(_Verbose):
self.__cond = Condition(Lock()) self.__cond = Condition(Lock())
self.__value = value self.__value = value
def __context__(self):
return self
def acquire(self, blocking=1): def acquire(self, blocking=1):
rc = False rc = False
self.__cond.acquire() self.__cond.acquire()
@ -286,6 +308,8 @@ class _Semaphore(_Verbose):
self.__cond.release() self.__cond.release()
return rc return rc
__enter__ = acquire
def release(self): def release(self):
self.__cond.acquire() self.__cond.acquire()
self.__value = self.__value + 1 self.__value = self.__value + 1
@ -295,6 +319,11 @@ class _Semaphore(_Verbose):
self.__cond.notify() self.__cond.notify()
self.__cond.release() self.__cond.release()
def __exit__(self, t, v, tb):
self.release()
if t is not None:
raise t, v, tb
def BoundedSemaphore(*args, **kwargs): def BoundedSemaphore(*args, **kwargs):
return _BoundedSemaphore(*args, **kwargs) return _BoundedSemaphore(*args, **kwargs)

9
Misc/NEWS
View File

@ -36,6 +36,12 @@ Core and builtins
with_statement``. Use of 'with' as a variable will generate a warning. with_statement``. Use of 'with' as a variable will generate a warning.
Use of 'as' as a variable will also generate a warning (unless it's Use of 'as' as a variable will also generate a warning (unless it's
part of an import statement). part of an import statement).
The following objects have __context__ methods:
- The built-in file type.
- The thread.LockType type.
- The following types defined by the threading module:
Lock, RLock, Condition, Semaphore, BoundedSemaphore.
- The decimal.Context class.
- Fix the encodings package codec search function to only search - Fix the encodings package codec search function to only search
inside its own package. Fixes problem reported in patch #1433198. inside its own package. Fixes problem reported in patch #1433198.
@ -411,6 +417,9 @@ Extension Modules
Library Library
------- -------
- PEP 343: new module contextlib.py defines decorator @contextmanager
and helpful context managers nested() and closing().
- The compiler package now supports future imports after the module docstring. - The compiler package now supports future imports after the module docstring.
- Bug #1413790: zipfile now sanitizes absolute archive names that are - Bug #1413790: zipfile now sanitizes absolute archive names that are

36
Modules/threadmodule.c
View File

@ -116,6 +116,36 @@ PyDoc_STRVAR(locked_doc,
\n\ \n\
Return whether the lock is in the locked state."); Return whether the lock is in the locked state.");
static PyObject *
lock_context(lockobject *self)
{
Py_INCREF(self);
return (PyObject *)self;
}
PyDoc_STRVAR(lock_exit_doc,
"__exit__(type, value, tb)\n\
\n\
Releases the lock; then re-raises the exception if type is not None.");
static PyObject *
lock_exit(lockobject *self, PyObject *args)
{
PyObject *type, *value, *tb, *result;
if (!PyArg_ParseTuple(args, "OOO:__exit__", &type, &value, &tb))
return NULL;
result = lock_PyThread_release_lock(self);
if (result != NULL && type != Py_None) {
Py_DECREF(result);
result = NULL;
Py_INCREF(type);
Py_INCREF(value);
Py_INCREF(tb);
PyErr_Restore(type, value, tb);
}
return result;
}
static PyMethodDef lock_methods[] = { static PyMethodDef lock_methods[] = {
{"acquire_lock", (PyCFunction)lock_PyThread_acquire_lock, {"acquire_lock", (PyCFunction)lock_PyThread_acquire_lock,
METH_VARARGS, acquire_doc}, METH_VARARGS, acquire_doc},
@ -129,6 +159,12 @@ static PyMethodDef lock_methods[] = {
METH_NOARGS, locked_doc}, METH_NOARGS, locked_doc},
{"locked", (PyCFunction)lock_locked_lock, {"locked", (PyCFunction)lock_locked_lock,
METH_NOARGS, locked_doc}, METH_NOARGS, locked_doc},
{"__context__", (PyCFunction)lock_context,
METH_NOARGS, PyDoc_STR("__context__() -> self.")},
{"__enter__", (PyCFunction)lock_PyThread_acquire_lock,
METH_VARARGS, acquire_doc},
{"__exit__", (PyCFunction)lock_exit,
METH_VARARGS, lock_exit_doc},
{NULL, NULL} /* sentinel */ {NULL, NULL} /* sentinel */
}; };

40
Objects/fileobject.c
View File

@ -1609,7 +1609,7 @@ file_writelines(PyFileObject *f, PyObject *seq)
} }
static PyObject * static PyObject *
file_getiter(PyFileObject *f) file_self(PyFileObject *f)
{ {
if (f->f_fp == NULL) if (f->f_fp == NULL)
return err_closed(); return err_closed();
@ -1617,6 +1617,24 @@ file_getiter(PyFileObject *f)
return (PyObject *)f; return (PyObject *)f;
} }
static PyObject *
file_exit(PyFileObject *f, PyObject *args)
{
PyObject *type, *value, *tb, *result;
if (!PyArg_ParseTuple(args, "OOO:__exit__", &type, &value, &tb))
return NULL;
result = file_close(f);
if (result != NULL && type != Py_None) {
Py_DECREF(result);
result = NULL;
Py_INCREF(type);
Py_INCREF(value);
Py_INCREF(tb);
PyErr_Restore(type, value, tb);
}
return result;
}
PyDoc_STRVAR(readline_doc, PyDoc_STRVAR(readline_doc,
"readline([size]) -> next line from the file, as a string.\n" "readline([size]) -> next line from the file, as a string.\n"
"\n" "\n"
@ -1701,6 +1719,19 @@ PyDoc_STRVAR(close_doc,
PyDoc_STRVAR(isatty_doc, PyDoc_STRVAR(isatty_doc,
"isatty() -> true or false. True if the file is connected to a tty device."); "isatty() -> true or false. True if the file is connected to a tty device.");
PyDoc_STRVAR(context_doc,
"__context__() -> self.");
PyDoc_STRVAR(enter_doc,
"__enter__() -> self.");
PyDoc_STRVAR(exit_doc,
"__exit__(type, value, traceback).\n\
\n\
Closes the file; then re-raises the exception if type is not None.\n\
If no exception is re-raised, the return value is the same as for close().\n\
");
static PyMethodDef file_methods[] = { static PyMethodDef file_methods[] = {
{"readline", (PyCFunction)file_readline, METH_VARARGS, readline_doc}, {"readline", (PyCFunction)file_readline, METH_VARARGS, readline_doc},
{"read", (PyCFunction)file_read, METH_VARARGS, read_doc}, {"read", (PyCFunction)file_read, METH_VARARGS, read_doc},
@ -1713,11 +1744,14 @@ static PyMethodDef file_methods[] = {
{"tell", (PyCFunction)file_tell, METH_NOARGS, tell_doc}, {"tell", (PyCFunction)file_tell, METH_NOARGS, tell_doc},
{"readinto", (PyCFunction)file_readinto, METH_VARARGS, readinto_doc}, {"readinto", (PyCFunction)file_readinto, METH_VARARGS, readinto_doc},
{"readlines", (PyCFunction)file_readlines,METH_VARARGS, readlines_doc}, {"readlines", (PyCFunction)file_readlines,METH_VARARGS, readlines_doc},
{"xreadlines",(PyCFunction)file_getiter, METH_NOARGS, xreadlines_doc}, {"xreadlines",(PyCFunction)file_self, METH_NOARGS, xreadlines_doc},
{"writelines",(PyCFunction)file_writelines, METH_O, writelines_doc}, {"writelines",(PyCFunction)file_writelines, METH_O, writelines_doc},
{"flush", (PyCFunction)file_flush, METH_NOARGS, flush_doc}, {"flush", (PyCFunction)file_flush, METH_NOARGS, flush_doc},
{"close", (PyCFunction)file_close, METH_NOARGS, close_doc}, {"close", (PyCFunction)file_close, METH_NOARGS, close_doc},
{"isatty", (PyCFunction)file_isatty, METH_NOARGS, isatty_doc}, {"isatty", (PyCFunction)file_isatty, METH_NOARGS, isatty_doc},
{"__context__", (PyCFunction)file_self, METH_NOARGS, context_doc},
{"__enter__", (PyCFunction)file_self, METH_NOARGS, enter_doc},
{"__exit__", (PyCFunction)file_exit, METH_VARARGS, exit_doc},
{NULL, NULL} /* sentinel */ {NULL, NULL} /* sentinel */
}; };
@ -2044,7 +2078,7 @@ PyTypeObject PyFile_Type = {
0, /* tp_clear */ 0, /* tp_clear */
0, /* tp_richcompare */ 0, /* tp_richcompare */
offsetof(PyFileObject, weakreflist), /* tp_weaklistoffset */ offsetof(PyFileObject, weakreflist), /* tp_weaklistoffset */
(getiterfunc)file_getiter, /* tp_iter */ (getiterfunc)file_self, /* tp_iter */
(iternextfunc)file_iternext, /* tp_iternext */ (iternextfunc)file_iternext, /* tp_iternext */
file_methods, /* tp_methods */ file_methods, /* tp_methods */
file_memberlist, /* tp_members */ file_memberlist, /* tp_members */

26
Python/ceval.c
View File

@ -2200,23 +2200,37 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throw)
The code here just sets the stack up for the call; The code here just sets the stack up for the call;
separate CALL_FUNCTION(3) and POP_TOP opcodes are separate CALL_FUNCTION(3) and POP_TOP opcodes are
emitted by the compiler. emitted by the compiler.
In addition, if the stack represents an exception,
we "zap" this information; __exit__() should
re-raise the exception if it wants to, and if
__exit__() returns normally, END_FINALLY should
*not* re-raise the exception. (But non-local
gotos should still be resumed.)
*/ */
x = TOP(); x = TOP();
u = SECOND(); u = SECOND();
if (PyInt_Check(u) || u == Py_None) { if (PyInt_Check(u) || u == Py_None) {
u = v = w = Py_None; u = v = w = Py_None;
Py_INCREF(u);
Py_INCREF(v);
Py_INCREF(w);
} }
else { else {
v = THIRD(); v = THIRD();
w = FOURTH(); w = FOURTH();
/* Zap the exception from the stack,
to fool END_FINALLY. */
STACKADJ(-2);
SET_TOP(x);
Py_INCREF(Py_None);
SET_SECOND(Py_None);
} }
Py_INCREF(u); STACKADJ(3);
Py_INCREF(v); SET_THIRD(u);
Py_INCREF(w); SET_SECOND(v);
PUSH(u); SET_TOP(w);
PUSH(v);
PUSH(w);
break; break;
} }

1
Python/errors.c
View File

@ -24,6 +24,7 @@ PyErr_Restore(PyObject *type, PyObject *value, PyObject *traceback)
if (traceback != NULL && !PyTraceBack_Check(traceback)) { if (traceback != NULL && !PyTraceBack_Check(traceback)) {
/* XXX Should never happen -- fatal error instead? */ /* XXX Should never happen -- fatal error instead? */
/* Well, it could be None. */
Py_DECREF(traceback); Py_DECREF(traceback);
traceback = NULL; traceback = NULL;
} }