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Reset the interactive namespace __warningregistry__ before executing code...
Reset the interactive namespace __warningregistry__ before executing code Fixes #6611. Idea: Right now, people often don't see important warnings when running code in IPython, because (to a first approximation) any given warning will only issue once per session. Blink and you'll miss it! This is a very common contributor to confused emails to numpy-discussion. E.g.: In [5]: 1 / my_array_with_random_contents /home/njs/.user-python2.7-64bit-3/bin/ipython:1: RuntimeWarning: divide by zero encountered in divide #!/home/njs/.user-python2.7-64bit-3/bin/python Out[5]: array([ 1.77073316, -2.29765021, -2.01800811, ..., 1.13871243, -1.08302964, -8.6185091 ]) Oo, right, guess I gotta be careful of those zeros -- thanks, numpy, for giving me that warning! A few days later: In [592]: 1 / some_other_array Out[592]: array([ 3.07735763, 0.50769289, 0.83984078, ..., -0.67563917, -0.85736257, -1.36511271]) Oops, it turns out that this array had a zero in it too, and that's going to bite me later. But no warning this time! The effect of this commit is to make it so that warnings triggered by the code in cell 5 do *not* suppress warnings triggered by the code in cell 592. Note that this only applies to warnings triggered *directly* by code entered interactively -- if somepkg.foo() calls anotherpkg.bad_func() which issues a warning, then this warning will still only be displayed once, even if multiple cells call somepkg.foo(). But if cell 5 and cell 592 both call anotherpkg.bad_func() directly, then both will get warnings. (Important exception: if foo() is defined *interactively*, and calls anotherpkg.bad_func(), then every cell that calls foo() will display the warning again. This is unavoidable without fixes to CPython upstream.) Explanation: Python's warning system has some weird quirks. By default, it tries to suppress duplicate warnings, where "duplicate" means the same warning message triggered twice by the same line of code. This requires determining which line of code is responsible for triggering a warning, and this is controlled by the stacklevel= argument to warnings.warn. Basically, though, the idea is that if foo() calls bar() which calls baz() which calls some_deprecated_api(), then baz() will get counted as being "responsible", and the warning system will make a note that the usage of some_deprecated_api() inside baz() has already been warned about and doesn't need to be warned about again. So far so good. To accomplish this, obviously, there has to be a record of somewhere which line this was. You might think that this would be done by recording the filename:linenumber pair in a dict inside the warnings module, or something like that. You would be wrong. What actually happens is that the warnings module will use stack introspection to reach into baz()'s execution environment, create a global (module-level) variable there named __warningregistry__, and then, inside this dictionary, record just the line number. Basically, it assumes that any given module contains only one line 1, only one line 2, etc., so storing the filename is irrelevant. Obviously for interactive code this is totally wrong -- all cells share the same execution environment and global namespace, and they all contain a new line 1. Currently the warnings module treats these as if they were all the same line. In fact they are not the same line; once we have executed a given chunk of code, we will never see those particular lines again. As soon as a given chunk of code finishes executing, its line number labels become meaningless, and the corresponding warning registry entries become meaningless as well. Therefore, with this patch we delete the __warningregistry__ each time we execute a new block of code.

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test_handlers.py
97 lines | 3.2 KiB | text/x-python | PythonLexer
"""Tests for input handlers.
"""
#-----------------------------------------------------------------------------
# Module imports
#-----------------------------------------------------------------------------
# third party
import nose.tools as nt
# our own packages
from IPython.core import autocall
from IPython.testing import tools as tt
from IPython.testing.globalipapp import get_ipython
from IPython.utils import py3compat
#-----------------------------------------------------------------------------
# Globals
#-----------------------------------------------------------------------------
# Get the public instance of IPython
ip = get_ipython()
failures = []
num_tests = 0
#-----------------------------------------------------------------------------
# Test functions
#-----------------------------------------------------------------------------
class CallableIndexable(object):
def __getitem__(self, idx): return True
def __call__(self, *args, **kws): return True
class Autocallable(autocall.IPyAutocall):
def __call__(self):
return "called"
def run(tests):
"""Loop through a list of (pre, post) inputs, where pre is the string
handed to ipython, and post is how that string looks after it's been
transformed (i.e. ipython's notion of _i)"""
tt.check_pairs(ip.prefilter_manager.prefilter_lines, tests)
def test_handlers():
call_idx = CallableIndexable()
ip.user_ns['call_idx'] = call_idx
# For many of the below, we're also checking that leading whitespace
# turns off the esc char, which it should unless there is a continuation
# line.
run([(i,py3compat.u_format(o)) for i,o in \
[('"no change"', '"no change"'), # normal
(u"lsmagic", "get_ipython().magic({u}'lsmagic ')"), # magic
#("a = b # PYTHON-MODE", '_i'), # emacs -- avoids _in cache
]])
# Objects which are instances of IPyAutocall are *always* autocalled
autocallable = Autocallable()
ip.user_ns['autocallable'] = autocallable
# auto
ip.magic('autocall 0')
# Only explicit escapes or instances of IPyAutocallable should get
# expanded
run([
('len "abc"', 'len "abc"'),
('autocallable', 'autocallable()'),
# Don't add extra brackets (gh-1117)
('autocallable()', 'autocallable()'),
])
ip.magic('autocall 1')
run([
('len "abc"', 'len("abc")'),
('len "abc";', 'len("abc");'), # ; is special -- moves out of parens
# Autocall is turned off if first arg is [] and the object
# is both callable and indexable. Like so:
('len [1,2]', 'len([1,2])'), # len doesn't support __getitem__...
('call_idx [1]', 'call_idx [1]'), # call_idx *does*..
('call_idx 1', 'call_idx(1)'),
('len', 'len'), # only at 2 does it auto-call on single args
])
ip.magic('autocall 2')
run([
('len "abc"', 'len("abc")'),
('len "abc";', 'len("abc");'),
('len [1,2]', 'len([1,2])'),
('call_idx [1]', 'call_idx [1]'),
('call_idx 1', 'call_idx(1)'),
# This is what's different:
('len', 'len()'), # only at 2 does it auto-call on single args
])
ip.magic('autocall 1')
nt.assert_equal(failures, [])