New submission from Benjamin S Wolf jokeser...@gmail.com:
(Python 3.2.3)
1. After discarding the module run_path used to run the code in, all references
to variables from local scopes (even if they are references to global
variables) are bound to None, preventing any code in functions from running
properly.
/tmp/a.py --
FOO = 'bar'
def f():
print(FOO)
f()
/tmp/b.py --
# Hack needed for:
# python3 /tmp/b.py,
# python3 -m /tmp/b
# runpy.run_path('/tmp/b.py')
from os.path import dirname
__path__ = [dirname(__file__)]
del dirname
# Hack needed for:
# python3 -m /tmp/b
if __name__ == '__main__' and not __package__:
__package__ = '__main__'
from . import a
def g():
print(a.FOO)
g()
~$ python3
import runpy
d = runpy.run_module('/tmp/a')
bar
d2 = runpy.run_path('/tmp/a.py')
bar
d['f']
function f at 0xb7451b6c
d['FOO']
'bar'
d['f']()
bar
d2['f']
function f at 0xb7451bac
d2['FOO']
'bar'
d2['f']()
None
d3 = runpy.run_path('/tmp/b.py')
bar
bar
d3['g']
function g at 0xb746e26c
d3['a']
module 'run_path.a' from '/tmp/a.py'
d3['g']()
Traceback (most recent call last):
File stdin, line 1, in module
File /tmp/b.py, line 15, in g
print(a.FOO)
AttributeError: 'NoneType' object has no attribute 'FOO'
Notice that run_module gets this right, as d['f']() prints 'bar' but d2['f']()
and d3['g']() do not.
2. run_path pollutes the module namespace when running a module that uses
relative imports. This prevents any code that imports the same module in the
same manner from running.
Continuing from #1 without having closed the interpreter:
d4 = runpy.run_path('/tmp/b.py')
Traceback (most recent call last):
File stdin, line 1, in module
File /usr/lib/python3.2/runpy.py, line 250, in run_path
return _run_module_code(code, init_globals, run_name, path_name)
File /usr/lib/python3.2/runpy.py, line 83, in _run_module_code
mod_name, mod_fname, mod_loader, pkg_name)
File /usr/lib/python3.2/runpy.py, line 73, in _run_code
exec(code, run_globals)
File /tmp/b.py, line 12, in module
from . import a
ImportError: cannot import name a
'run_path' in sys.modules
False
'run_path.a' in sys.modules
True
d3['a'].f()
bar
del sys.modules['run_path.a']
d4 = runpy.run_path('/tmp/b.py')
bar
bar
run_module, on the other hand, also alters sys.modules, but this does not
prevent the module from being run, only from the secondary module from being
re-imported:
[Create an empty file /tmp/__init__.py]
sys.path = ['/'] + sys.path
d5 = runpy.run_module('tmp.b')
bar
bar
d6 = runpy.run_module('tmp.b')
bar
d7 = runpy.run_module('tmp.b')
bar
'tmp' in sys.modules
True
'tmp.b' in sys.modules
False
'tmp.a' in sys.modules
True
[This was the only way I could get run_module to run /tmp/b.py, regardless of
the presence or lack of the path and __package__ hacks at the top of the file,
or any other changes I've experimented with. runpy.run_module('/tmp/b'),
runpy.run_module('b') [with '/tmp' in sys.path] would generally result in:
ValueError: Attempted relative import in non-package
and setting run_name='__main__' alongside any of the other changes would result
in:
ImportError: cannot import name a
python3 /tmp/b.py and python3 -m /tmp/b run fine.]
3. And finally, an examination of the run_path code shows that it doesn't, as
the docs indicate, set __package__ to be run_name.rpartition('.')[0], but
either the empty string or None:
http://hg.python.org/cpython/file/3.2/Lib/runpy.py#l269
--
components: Library (Lib)
messages: 164437
nosy: Benjamin.S.Wolf
priority: normal
severity: normal
status: open
title: runpy.run_path broken: Breaks scoping; pollutes sys.modules; doesn't set
__package__
type: behavior
versions: Python 3.2
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http://bugs.python.org/issue15230
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