Mercurial > cpython-lru_cache-weakref
diff Python/compile.c @ 64620:25cc226dc9bd
#4617: Previously it was illegal to delete a name from the local
namespace if it occurs as a free variable in a nested block. This limitation
of the compiler has been lifted, and a new opcode introduced (DELETE_DEREF).
This sample was valid in 2.6, but fails to compile in 3.x without this change::
>>> def f():
... def print_error():
... print(e)
... try:
... something
... except Exception as e:
... print_error()
... # implicit "del e" here
This sample has always been invalid in Python, and now works::
>>> def outer(x):
... def inner():
... return x
... inner()
... del x
There is no need to bump the PYC magic number: the new opcode is used
for code that did not compile before.
| author | Amaury Forgeot d'Arc <amauryfa@gmail.com> |
|---|---|
| date | Fri, 10 Sep 2010 21:39:53 +0000 |
| parents | 725231211273 |
| children | 861c35cef7aa |
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line diff
--- a/Python/compile.c Fri Sep 10 20:43:53 2010 +0000 +++ b/Python/compile.c Fri Sep 10 21:39:53 2010 +0000 @@ -857,6 +857,8 @@ return 1; case STORE_DEREF: return -1; + case DELETE_DEREF: + return 0; default: fprintf(stderr, "opcode = %d\n", opcode); Py_FatalError("opcode_stack_effect()"); @@ -2506,13 +2508,7 @@ case AugLoad: case AugStore: break; - case Del: - PyErr_Format(PyExc_SyntaxError, - "can not delete variable '%S' referenced " - "in nested scope", - name); - Py_DECREF(mangled); - return 0; + case Del: op = DELETE_DEREF; break; case Param: default: PyErr_SetString(PyExc_SystemError,