Georg Brandl wrote:
> Current trunk:
>
>>>> with 1:
> ... print "1"
> ...
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> AttributeError: 'int' object has no attribute '__exit__'
>
> Isn't that a bit crude? For "for i in 1" there's a better
> error message, so why shouldn't the above give a
> TypeError: 'int' object is not a context manager
The for loop has a nice error message because it starts with its own opcode,
but the with statement translates pretty much to the code in PEP 343. There's
a special opcode at the end to help with unwinding the stack, but at the start
it's just normal attribute retrieval opcodes for __enter__ and __exit__.
>>> def f():
... with 1:
... pass
...
>>> dis.dis(f)
2 0 LOAD_CONST 1 (1)
3 DUP_TOP
4 LOAD_ATTR 0 (__exit__)
7 STORE_FAST 0 (_[1])
10 LOAD_ATTR 1 (__enter__)
13 CALL_FUNCTION 0
16 POP_TOP
17 SETUP_FINALLY 4 (to 24)
3 20 POP_BLOCK
21 LOAD_CONST 0 (None)
>> 24 LOAD_FAST 0 (_[1])
27 DELETE_FAST 0 (_[1])
30 WITH_CLEANUP
31 END_FINALLY
32 LOAD_CONST 0 (None)
35 RETURN_VALUE
Cheers,
Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
---------------------------------------------------------------
http://www.boredomandlaziness.org
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
