usage patterns to be encapsulated for convenient reuse.
.. productionlist::
- with_stmt: "with" `expression` ["as" `target`] ":" `suite`
+ with_stmt: "with" with_item ("," with_item)* ":" `suite`
+ with_item: `expression` ["as" `target`]
-The execution of the :keyword:`with` statement proceeds as follows:
+The execution of the :keyword:`with` statement with one "item" proceeds as follows:
#. The context expression is evaluated to obtain a context manager.
value from :meth:`__exit__` is ignored, and execution proceeds at the normal
location for the kind of exit that was taken.
+With more than one item, the context managers are processed as if multiple
+:keyword:`with` statements were nested::
+
+ with A() as a, B() as b:
+ suite
+
+is equivalent to ::
+
+ with A() as a:
+ with B() as b:
+ suite
+
+.. versionchanged:: 3.1
+ Support for multiple context expressions.
+
.. seealso::
:pep:`0343` - The "with" statement
['else' ':' suite]
['finally' ':' suite] |
'finally' ':' suite))
-with_stmt: 'with' test [ with_var ] ':' suite
-with_var: 'as' expr
+with_stmt: 'with' with_item (',' with_item)* ':' suite
+with_item: test ['as' expr]
# NB compile.c makes sure that the default except clause is last
except_clause: 'except' [test ['as' NAME]]
suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
#define for_stmt 295
#define try_stmt 296
#define with_stmt 297
-#define with_var 298
+#define with_item 298
#define except_clause 299
#define suite 300
#define test 301
def test_with(self):
self.check_suite("with open('x'): pass\n")
self.check_suite("with open('x') as f: pass\n")
+ self.check_suite("with open('x') as f, open('y') as g: pass\n")
def test_try_stmt(self):
self.check_suite("try: pass\nexcept: pass\n")
self.fail("ZeroDivisionError should have been raised")
+class NestedWith(unittest.TestCase):
+
+ class Dummy(object):
+ def __init__(self, value=None, gobble=False):
+ if value is None:
+ value = self
+ self.value = value
+ self.gobble = gobble
+ self.enter_called = False
+ self.exit_called = False
+
+ def __enter__(self):
+ self.enter_called = True
+ return self.value
+
+ def __exit__(self, *exc_info):
+ self.exit_called = True
+ self.exc_info = exc_info
+ if self.gobble:
+ return True
+
+ class CtorRaises(object):
+ def __init__(self): raise RuntimeError()
+
+ class EnterRaises(object):
+ def __enter__(self): raise RuntimeError()
+ def __exit__(self, *exc_info): pass
+
+ class ExitRaises(object):
+ def __enter__(self): pass
+ def __exit__(self, *exc_info): raise RuntimeError()
+
+ def testNoExceptions(self):
+ with self.Dummy() as a, self.Dummy() as b:
+ self.assertTrue(a.enter_called)
+ self.assertTrue(b.enter_called)
+ self.assertTrue(a.exit_called)
+ self.assertTrue(b.exit_called)
+
+ def testExceptionInExprList(self):
+ try:
+ with self.Dummy() as a, self.CtorRaises():
+ pass
+ except:
+ pass
+ self.assertTrue(a.enter_called)
+ self.assertTrue(a.exit_called)
+
+ def testExceptionInEnter(self):
+ try:
+ with self.Dummy() as a, self.EnterRaises():
+ self.fail('body of bad with executed')
+ except RuntimeError:
+ pass
+ else:
+ self.fail('RuntimeError not reraised')
+ self.assertTrue(a.enter_called)
+ self.assertTrue(a.exit_called)
+
+ def testExceptionInExit(self):
+ body_executed = False
+ with self.Dummy(gobble=True) as a, self.ExitRaises():
+ body_executed = True
+ self.assertTrue(a.enter_called)
+ self.assertTrue(a.exit_called)
+ self.assertNotEqual(a.exc_info[0], None)
+
+ def testEnterReturnsTuple(self):
+ with self.Dummy(value=(1,2)) as (a1, a2), \
+ self.Dummy(value=(10, 20)) as (b1, b2):
+ self.assertEquals(1, a1)
+ self.assertEquals(2, a2)
+ self.assertEquals(10, b1)
+ self.assertEquals(20, b2)
+
def test_main():
run_unittest(FailureTestCase, NonexceptionalTestCase,
NestedNonexceptionalTestCase, ExceptionalTestCase,
NonLocalFlowControlTestCase,
AssignmentTargetTestCase,
- ExitSwallowsExceptionTestCase)
+ ExitSwallowsExceptionTestCase,
+ NestedWith)
if __name__ == '__main__':
- Issue #6089: Fixed str.format with certain invalid field specifiers
that would raise SystemError.
+- Added support for multiple context managers in the same with statement.
+
- Issue #5829: complex("1e500") no longer raises OverflowError. This
makes it consistent with float("1e500") and interpretation of real
and imaginary literals.
return ok;
}
-/* with_var
-with_var: 'as' expr
+/* with_item:
+ * test ['as' expr]
*/
static int
-validate_with_var(node *tree)
+validate_with_item(node *tree)
{
int nch = NCH(tree);
- int ok = (validate_ntype(tree, with_var)
- && (nch == 2)
- && validate_name(CHILD(tree, 0), "as")
- && validate_expr(CHILD(tree, 1)));
- return ok;
+ int ok = (validate_ntype(tree, with_item)
+ && (nch == 1 || nch == 3)
+ && validate_test(CHILD(tree, 0)));
+ if (ok && nch == 3)
+ ok = (validate_name(CHILD(tree, 1), "as")
+ && validate_expr(CHILD(tree, 2)));
+ return ok;
}
-/* with_stmt
- * 0 1 2 -2 -1
-with_stmt: 'with' test [ with_var ] ':' suite
+/* with_stmt:
+ * 0 1 ... -2 -1
+ * 'with' with_item (',' with_item)* ':' suite
*/
static int
validate_with_stmt(node *tree)
{
+ int i;
int nch = NCH(tree);
int ok = (validate_ntype(tree, with_stmt)
- && ((nch == 4) || (nch == 5))
+ && (nch % 2 == 0)
&& validate_name(CHILD(tree, 0), "with")
- && validate_test(CHILD(tree, 1))
- && (nch == 4 || validate_with_var(CHILD(tree, 2)))
&& validate_colon(RCHILD(tree, -2))
&& validate_suite(RCHILD(tree, -1)));
- return ok;
+ for (i = 1; ok && i < nch - 2; i += 2)
+ ok = validate_with_item(CHILD(tree, i));
+ return ok;
}
/* funcdef:
return TryFinally(body, finally, LINENO(n), n->n_col_offset, c->c_arena);
}
-static expr_ty
-ast_for_with_var(struct compiling *c, const node *n)
-{
- REQ(n, with_var);
- return ast_for_expr(c, CHILD(n, 1));
-}
-
-/* with_stmt: 'with' test [ with_var ] ':' suite */
+/* with_item: test ['as' expr] */
static stmt_ty
-ast_for_with_stmt(struct compiling *c, const node *n)
+ast_for_with_item(struct compiling *c, const node *n, asdl_seq *content)
{
expr_ty context_expr, optional_vars = NULL;
- int suite_index = 3; /* skip 'with', test, and ':' */
- asdl_seq *suite_seq;
- assert(TYPE(n) == with_stmt);
- context_expr = ast_for_expr(c, CHILD(n, 1));
- if (TYPE(CHILD(n, 2)) == with_var) {
- optional_vars = ast_for_with_var(c, CHILD(n, 2));
+ REQ(n, with_item);
+ context_expr = ast_for_expr(c, CHILD(n, 0));
+ if (NCH(n) == 3) {
+ optional_vars = ast_for_expr(c, CHILD(n, 2));
if (!optional_vars) {
return NULL;
if (!set_context(c, optional_vars, Store, n)) {
return NULL;
}
- suite_index = 4;
}
- suite_seq = ast_for_suite(c, CHILD(n, suite_index));
- if (!suite_seq) {
+ return With(context_expr, optional_vars, content, LINENO(n),
+ n->n_col_offset, c->c_arena);
+}
+
+/* with_stmt: 'with' with_item (',' with_item)* ':' suite */
+static stmt_ty
+ast_for_with_stmt(struct compiling *c, const node *n)
+{
+ int i;
+ stmt_ty ret;
+ asdl_seq *inner;
+
+ REQ(n, with_stmt);
+
+ /* process the with items inside-out */
+ i = NCH(n) - 1;
+ /* the suite of the innermost with item is the suite of the with stmt */
+ inner = ast_for_suite(c, CHILD(n, i));
+ if (!inner)
return NULL;
+
+ for (;;) {
+ i -= 2;
+ ret = ast_for_with_item(c, CHILD(n, i), inner);
+ if (!ret)
+ return NULL;
+ /* was this the last item? */
+ if (i == 1)
+ break;
+ /* if not, wrap the result so far in a new sequence */
+ inner = asdl_seq_new(1, c->c_arena);
+ if (!inner)
+ return NULL;
+ asdl_seq_SET(inner, 0, ret);
}
- return With(context_expr, optional_vars, suite_seq, LINENO(n),
- n->n_col_offset, c->c_arena);
+
+ return ret;
}
static stmt_ty
{99, 1},
};
static arc arcs_41_1[1] = {
- {24, 2},
+ {100, 2},
};
static arc arcs_41_2[2] = {
- {100, 3},
- {25, 4},
+ {30, 1},
+ {25, 3},
};
static arc arcs_41_3[1] = {
- {25, 4},
+ {26, 4},
};
static arc arcs_41_4[1] = {
- {26, 5},
-};
-static arc arcs_41_5[1] = {
- {0, 5},
+ {0, 4},
};
-static state states_41[6] = {
+static state states_41[5] = {
{1, arcs_41_0},
{1, arcs_41_1},
{2, arcs_41_2},
{1, arcs_41_3},
{1, arcs_41_4},
- {1, arcs_41_5},
};
static arc arcs_42_0[1] = {
- {80, 1},
+ {24, 1},
};
-static arc arcs_42_1[1] = {
- {101, 2},
+static arc arcs_42_1[2] = {
+ {80, 2},
+ {0, 1},
};
static arc arcs_42_2[1] = {
- {0, 2},
+ {101, 3},
+};
+static arc arcs_42_3[1] = {
+ {0, 3},
};
-static state states_42[3] = {
+static state states_42[4] = {
{1, arcs_42_0},
- {1, arcs_42_1},
+ {2, arcs_42_1},
{1, arcs_42_2},
+ {1, arcs_42_3},
};
static arc arcs_43_0[1] = {
{102, 1},
"\000\000\000\000\000\000\000\000\000\000\000\100\000\000\000\000\000\000\000\000\000"},
{296, "try_stmt", 0, 13, states_40,
"\000\000\000\000\000\000\000\000\000\000\000\000\001\000\000\000\000\000\000\000\000"},
- {297, "with_stmt", 0, 6, states_41,
+ {297, "with_stmt", 0, 5, states_41,
"\000\000\000\000\000\000\000\000\000\000\000\000\010\000\000\000\000\000\000\000\000"},
- {298, "with_var", 0, 3, states_42,
- "\000\000\000\000\000\000\000\000\000\000\001\000\000\000\000\000\000\000\000\000\000"},
+ {298, "with_item", 0, 4, states_42,
+ "\000\040\040\200\000\000\000\000\000\040\000\000\000\040\004\000\000\103\050\037\000"},
{299, "except_clause", 0, 5, states_43,
"\000\000\000\000\000\000\000\000\000\000\000\000\100\000\000\000\000\000\000\000\000"},
{300, "suite", 0, 5, states_44,
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