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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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alias.py
253 lines | 9.6 KiB | text/x-python | PythonLexer
# encoding: utf-8
"""
System command aliases.
Authors:
* Fernando Perez
* 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.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import os
import re
import sys
from IPython.config.configurable import Configurable
from IPython.core.error import UsageError
from IPython.utils.py3compat import string_types
from IPython.utils.traitlets import List, Instance
from IPython.utils.warn import error
#-----------------------------------------------------------------------------
# Utilities
#-----------------------------------------------------------------------------
# This is used as the pattern for calls to split_user_input.
shell_line_split = re.compile(r'^(\s*)()(\S+)(.*$)')
def default_aliases():
"""Return list of shell aliases to auto-define.
"""
# Note: the aliases defined here should be safe to use on a kernel
# regardless of what frontend it is attached to. Frontends that use a
# kernel in-process can define additional aliases that will only work in
# their case. For example, things like 'less' or 'clear' that manipulate
# the terminal should NOT be declared here, as they will only work if the
# kernel is running inside a true terminal, and not over the network.
if os.name == 'posix':
default_aliases = [('mkdir', 'mkdir'), ('rmdir', 'rmdir'),
('mv', 'mv'), ('rm', 'rm'), ('cp', 'cp'),
('cat', 'cat'),
]
# Useful set of ls aliases. The GNU and BSD options are a little
# different, so we make aliases that provide as similar as possible
# behavior in ipython, by passing the right flags for each platform
if sys.platform.startswith('linux'):
ls_aliases = [('ls', 'ls -F --color'),
# long ls
('ll', 'ls -F -o --color'),
# ls normal files only
('lf', 'ls -F -o --color %l | grep ^-'),
# ls symbolic links
('lk', 'ls -F -o --color %l | grep ^l'),
# directories or links to directories,
('ldir', 'ls -F -o --color %l | grep /$'),
# things which are executable
('lx', 'ls -F -o --color %l | grep ^-..x'),
]
elif sys.platform.startswith('openbsd') or sys.platform.startswith('netbsd'):
# OpenBSD, NetBSD. The ls implementation on these platforms do not support
# the -G switch and lack the ability to use colorized output.
ls_aliases = [('ls', 'ls -F'),
# long ls
('ll', 'ls -F -l'),
# ls normal files only
('lf', 'ls -F -l %l | grep ^-'),
# ls symbolic links
('lk', 'ls -F -l %l | grep ^l'),
# directories or links to directories,
('ldir', 'ls -F -l %l | grep /$'),
# things which are executable
('lx', 'ls -F -l %l | grep ^-..x'),
]
else:
# BSD, OSX, etc.
ls_aliases = [('ls', 'ls -F -G'),
# long ls
('ll', 'ls -F -l -G'),
# ls normal files only
('lf', 'ls -F -l -G %l | grep ^-'),
# ls symbolic links
('lk', 'ls -F -l -G %l | grep ^l'),
# directories or links to directories,
('ldir', 'ls -F -G -l %l | grep /$'),
# things which are executable
('lx', 'ls -F -l -G %l | grep ^-..x'),
]
default_aliases = default_aliases + ls_aliases
elif os.name in ['nt', 'dos']:
default_aliases = [('ls', 'dir /on'),
('ddir', 'dir /ad /on'), ('ldir', 'dir /ad /on'),
('mkdir', 'mkdir'), ('rmdir', 'rmdir'),
('echo', 'echo'), ('ren', 'ren'), ('copy', 'copy'),
]
else:
default_aliases = []
return default_aliases
class AliasError(Exception):
pass
class InvalidAliasError(AliasError):
pass
class Alias(object):
"""Callable object storing the details of one alias.
Instances are registered as magic functions to allow use of aliases.
"""
# Prepare blacklist
blacklist = {'cd','popd','pushd','dhist','alias','unalias'}
def __init__(self, shell, name, cmd):
self.shell = shell
self.name = name
self.cmd = cmd
self.nargs = self.validate()
def validate(self):
"""Validate the alias, and return the number of arguments."""
if self.name in self.blacklist:
raise InvalidAliasError("The name %s can't be aliased "
"because it is a keyword or builtin." % self.name)
try:
caller = self.shell.magics_manager.magics['line'][self.name]
except KeyError:
pass
else:
if not isinstance(caller, Alias):
raise InvalidAliasError("The name %s can't be aliased "
"because it is another magic command." % self.name)
if not (isinstance(self.cmd, string_types)):
raise InvalidAliasError("An alias command must be a string, "
"got: %r" % self.cmd)
nargs = self.cmd.count('%s')
if (nargs > 0) and (self.cmd.find('%l') >= 0):
raise InvalidAliasError('The %s and %l specifiers are mutually '
'exclusive in alias definitions.')
return nargs
def __repr__(self):
return "<alias {} for {!r}>".format(self.name, self.cmd)
def __call__(self, rest=''):
cmd = self.cmd
nargs = self.nargs
# Expand the %l special to be the user's input line
if cmd.find('%l') >= 0:
cmd = cmd.replace('%l', rest)
rest = ''
if nargs==0:
# Simple, argument-less aliases
cmd = '%s %s' % (cmd, rest)
else:
# Handle aliases with positional arguments
args = rest.split(None, nargs)
if len(args) < nargs:
raise UsageError('Alias <%s> requires %s arguments, %s given.' %
(self.name, nargs, len(args)))
cmd = '%s %s' % (cmd % tuple(args[:nargs]),' '.join(args[nargs:]))
self.shell.system(cmd)
#-----------------------------------------------------------------------------
# Main AliasManager class
#-----------------------------------------------------------------------------
class AliasManager(Configurable):
default_aliases = List(default_aliases(), config=True)
user_aliases = List(default_value=[], config=True)
shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
def __init__(self, shell=None, **kwargs):
super(AliasManager, self).__init__(shell=shell, **kwargs)
# For convenient access
self.linemagics = self.shell.magics_manager.magics['line']
self.init_aliases()
def init_aliases(self):
# Load default & user aliases
for name, cmd in self.default_aliases + self.user_aliases:
self.soft_define_alias(name, cmd)
@property
def aliases(self):
return [(n, func.cmd) for (n, func) in self.linemagics.items()
if isinstance(func, Alias)]
def soft_define_alias(self, name, cmd):
"""Define an alias, but don't raise on an AliasError."""
try:
self.define_alias(name, cmd)
except AliasError as e:
error("Invalid alias: %s" % e)
def define_alias(self, name, cmd):
"""Define a new alias after validating it.
This will raise an :exc:`AliasError` if there are validation
problems.
"""
caller = Alias(shell=self.shell, name=name, cmd=cmd)
self.shell.magics_manager.register_function(caller, magic_kind='line',
magic_name=name)
def get_alias(self, name):
"""Return an alias, or None if no alias by that name exists."""
aname = self.linemagics.get(name, None)
return aname if isinstance(aname, Alias) else None
def is_alias(self, name):
"""Return whether or not a given name has been defined as an alias"""
return self.get_alias(name) is not None
def undefine_alias(self, name):
if self.is_alias(name):
del self.linemagics[name]
else:
raise ValueError('%s is not an alias' % name)
def clear_aliases(self):
for name, cmd in self.aliases:
self.undefine_alias(name)
def retrieve_alias(self, name):
"""Retrieve the command to which an alias expands."""
caller = self.get_alias(name)
if caller:
return caller.cmd
else:
raise ValueError('%s is not an alias' % name)