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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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__init__.py
83 lines | 2.5 KiB | text/x-python | PythonLexer
/ IPython / nbformat / v2 / __init__.py
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"""The main API for the v2 notebook format.
Authors:
* Brian Granger
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2011 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import os
from .nbbase import (
NotebookNode,
new_code_cell, new_text_cell, new_notebook, new_output, new_worksheet,
new_metadata, new_author
)
from .nbjson import reads as reads_json, writes as writes_json
from .nbjson import reads as read_json, writes as write_json
from .nbjson import to_notebook as to_notebook_json
from .nbxml import reads as reads_xml
from .nbxml import reads as read_xml
from .nbxml import to_notebook as to_notebook_xml
from .nbpy import reads as reads_py, writes as writes_py
from .nbpy import reads as read_py, writes as write_py
from .nbpy import to_notebook as to_notebook_py
from .convert import downgrade, upgrade
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
nbformat = 2
nbformat_minor = 0
def parse_filename(fname):
"""Parse a notebook filename.
This function takes a notebook filename and returns the notebook
format (json/py) and the notebook name. This logic can be
summarized as follows:
* notebook.ipynb -> (notebook.ipynb, notebook, json)
* notebook.json -> (notebook.json, notebook, json)
* notebook.py -> (notebook.py, notebook, py)
* notebook -> (notebook.ipynb, notebook, json)
Parameters
----------
fname : unicode
The notebook filename. The filename can use a specific filename
extention (.ipynb, .json, .py) or none, in which case .ipynb will
be assumed.
Returns
-------
(fname, name, format) : (unicode, unicode, unicode)
The filename, notebook name and format.
"""
basename, ext = os.path.splitext(fname)
if ext == u'.ipynb':
format = u'json'
elif ext == u'.json':
format = u'json'
elif ext == u'.py':
format = u'py'
else:
basename = fname
fname = fname + u'.ipynb'
format = u'json'
return fname, basename, format