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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.
Matthias BUSSONNIER - - Load All Authors

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test_export.py
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/ IPython / nbconvert / exporters / tests / test_export.py
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"""
Module with tests for export.py
"""
#-----------------------------------------------------------------------------
# Copyright (c) 2013, the IPython Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import os
from IPython.nbformat import current as nbformat
from .base import ExportersTestsBase
from ..export import *
from ..python import PythonExporter
#-----------------------------------------------------------------------------
# Class
#-----------------------------------------------------------------------------
class TestExport(ExportersTestsBase):
"""Contains test functions for export.py"""
def test_export_wrong_name(self):
"""
Is the right error thrown when a bad template name is used?
"""
try:
export_by_name('not_a_name', self._get_notebook())
except ExporterNameError as e:
pass
def test_export_filename(self):
"""
Can a notebook be exported by filename?
"""
(output, resources) = export_by_name('python', self._get_notebook())
assert len(output) > 0
def test_export_nbnode(self):
"""
Can a notebook be exported by a notebook node handle?
"""
with open(self._get_notebook(), 'r') as f:
notebook = nbformat.read(f, 'json')
(output, resources) = export_by_name('python', notebook)
assert len(output) > 0
def test_export_filestream(self):
"""
Can a notebook be exported by a filesteam?
"""
with open(self._get_notebook(), 'r') as f:
(output, resources) = export_by_name('python', f)
assert len(output) > 0
def test_export_using_exporter(self):
"""
Can a notebook be exported using an instanciated exporter?
"""
(output, resources) = export(PythonExporter(), self._get_notebook())
assert len(output) > 0
def test_export_using_exporter_class(self):
"""
Can a notebook be exported using an exporter class type?
"""
(output, resources) = export(PythonExporter, self._get_notebook())
assert len(output) > 0
def test_export_resources(self):
"""
Can a notebook be exported along with a custom resources dict?
"""
(output, resources) = export(PythonExporter, self._get_notebook(), resources={})
assert len(output) > 0
def test_no_exporter(self):
"""
Is the right error thrown if no exporter is provided?
"""
try:
(output, resources) = export(None, self._get_notebook())
except TypeError:
pass