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Use a PEP562 implementation for deprecating attributes (Python-Markdo…
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…wn#757)

Use a vendored Pep562 backport to simulate Python 3.7's new PEP 562 feature. For Python3.7 and later, default to the official implementation.
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facelessuser authored and waylan committed Dec 22, 2018
1 parent aa6667e commit ab24c23
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1 change: 1 addition & 0 deletions .coveragerc
Original file line number Diff line number Diff line change
Expand Up @@ -3,3 +3,4 @@ omit=
*site-packages*
tests/*
markdown/test_tools.py
markdown/pep562.py
41 changes: 20 additions & 21 deletions markdown/__init__.py
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Expand Up @@ -23,8 +23,10 @@
from __future__ import absolute_import
from __future__ import unicode_literals
from .core import Markdown, markdown, markdownFromFile
from .util import ModuleWrap, deprecated
from .util import PY37
from .pep562 import Pep562
from pkg_resources.extern import packaging
import warnings

# For backward compatibility as some extensions expect it...
from .extensions import Extension # noqa
Expand Down Expand Up @@ -64,28 +66,25 @@ def _get_version(): # pragma: no cover

__version__ = _get_version()

__deprecated__ = {
"version": ("__version__", __version__),
"version_info": ("__version_info__", __version_info__)
}

class _ModuleWrap(ModuleWrap):
"""
Wrap module so that we can control `__getattribute__` and `__dir__` logic.

Treat `version` and `version_info` as deprecated properties.
Provides backward-compatabillity with <3.0 versions.
"""
def __getattr__(name):
"""Get attribute."""

@property
@deprecated("Use '__version__' instead.", stacklevel=3)
def version(self):
"""Get deprecated version."""
deprecated = __deprecated__.get(name)
if deprecated:
warnings.warn(
"'{}' is deprecated. Use '{}' instead.".format(name, deprecated[0]),
category=DeprecationWarning,
stacklevel=(3 if PY37 else 4)
)
return deprecated[1]
raise AttributeError("module '{}' has no attribute '{}'".format(__name__, name))

return __version__

@property
@deprecated("Use '__version_info__' instead.", stacklevel=3)
def version_info(self):
"""Get deprecated version info."""

return __version_info__


_ModuleWrap(__name__)
if not PY37:
Pep562(__name__)
246 changes: 246 additions & 0 deletions markdown/pep562.py
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@@ -0,0 +1,246 @@
"""
Backport of PEP 562.
https://pypi.org/search/?q=pep562
Licensed under MIT
Copyright (c) 2018 Isaac Muse <[email protected]>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
documentation files (the "Software"), to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions
of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
"""
from __future__ import unicode_literals
import sys
from collections import namedtuple
import re

__all__ = ('Pep562',)

RE_VER = re.compile(
r'''(?x)
(?P<major>\d+)(?:\.(?P<minor>\d+))?(?:\.(?P<micro>\d+))?
(?:(?P<type>a|b|rc)(?P<pre>\d+))?
(?:\.post(?P<post>\d+))?
(?:\.dev(?P<dev>\d+))?
'''
)

REL_MAP = {
".dev": "",
".dev-alpha": "a",
".dev-beta": "b",
".dev-candidate": "rc",
"alpha": "a",
"beta": "b",
"candidate": "rc",
"final": ""
}

DEV_STATUS = {
".dev": "2 - Pre-Alpha",
".dev-alpha": "2 - Pre-Alpha",
".dev-beta": "2 - Pre-Alpha",
".dev-candidate": "2 - Pre-Alpha",
"alpha": "3 - Alpha",
"beta": "4 - Beta",
"candidate": "4 - Beta",
"final": "5 - Production/Stable"
}

PRE_REL_MAP = {"a": 'alpha', "b": 'beta', "rc": 'candidate'}


class Version(namedtuple("Version", ["major", "minor", "micro", "release", "pre", "post", "dev"])):
"""
Get the version (PEP 440).
A biased approach to the PEP 440 semantic version.
Provides a tuple structure which is sorted for comparisons `v1 > v2` etc.
(major, minor, micro, release type, pre-release build, post-release build, development release build)
Release types are named in is such a way they are comparable with ease.
Accessors to check if a development, pre-release, or post-release build. Also provides accessor to get
development status for setup files.
How it works (currently):
- You must specify a release type as either `final`, `alpha`, `beta`, or `candidate`.
- To define a development release, you can use either `.dev`, `.dev-alpha`, `.dev-beta`, or `.dev-candidate`.
The dot is used to ensure all development specifiers are sorted before `alpha`.
You can specify a `dev` number for development builds, but do not have to as implicit development releases
are allowed.
- You must specify a `pre` value greater than zero if using a prerelease as this project (not PEP 440) does not
allow implicit prereleases.
- You can optionally set `post` to a value greater than zero to make the build a post release. While post releases
are technically allowed in prereleases, it is strongly discouraged, so we are rejecting them. It should be
noted that we do not allow `post0` even though PEP 440 does not restrict this. This project specifically
does not allow implicit post releases.
- It should be noted that we do not support epochs `1!` or local versions `+some-custom.version-1`.
Acceptable version releases:
```
Version(1, 0, 0, "final") 1.0
Version(1, 2, 0, "final") 1.2
Version(1, 2, 3, "final") 1.2.3
Version(1, 2, 0, ".dev-alpha", pre=4) 1.2a4
Version(1, 2, 0, ".dev-beta", pre=4) 1.2b4
Version(1, 2, 0, ".dev-candidate", pre=4) 1.2rc4
Version(1, 2, 0, "final", post=1) 1.2.post1
Version(1, 2, 3, ".dev") 1.2.3.dev0
Version(1, 2, 3, ".dev", dev=1) 1.2.3.dev1
```
"""

def __new__(cls, major, minor, micro, release="final", pre=0, post=0, dev=0):
"""Validate version info."""

# Ensure all parts are positive integers.
for value in (major, minor, micro, pre, post):
if not (isinstance(value, int) and value >= 0):
raise ValueError("All version parts except 'release' should be integers.")

if release not in REL_MAP:
raise ValueError("'{}' is not a valid release type.".format(release))

# Ensure valid pre-release (we do not allow implicit pre-releases).
if ".dev-candidate" < release < "final":
if pre == 0:
raise ValueError("Implicit pre-releases not allowed.")
elif dev:
raise ValueError("Version is not a development release.")
elif post:
raise ValueError("Post-releases are not allowed with pre-releases.")

# Ensure valid development or development/pre release
elif release < "alpha":
if release > ".dev" and pre == 0:
raise ValueError("Implicit pre-release not allowed.")
elif post:
raise ValueError("Post-releases are not allowed with pre-releases.")

# Ensure a valid normal release
else:
if pre:
raise ValueError("Version is not a pre-release.")
elif dev:
raise ValueError("Version is not a development release.")

return super(Version, cls).__new__(cls, major, minor, micro, release, pre, post, dev)

def _is_pre(self):
"""Is prerelease."""

return self.pre > 0

def _is_dev(self):
"""Is development."""

return bool(self.release < "alpha")

def _is_post(self):
"""Is post."""

return self.post > 0

def _get_dev_status(self): # pragma: no cover
"""Get development status string."""

return DEV_STATUS[self.release]

def _get_canonical(self):
"""Get the canonical output string."""

# Assemble major, minor, micro version and append `pre`, `post`, or `dev` if needed..
if self.micro == 0:
ver = "{}.{}".format(self.major, self.minor)
else:
ver = "{}.{}.{}".format(self.major, self.minor, self.micro)
if self._is_pre():
ver += '{}{}'.format(REL_MAP[self.release], self.pre)
if self._is_post():
ver += ".post{}".format(self.post)
if self._is_dev():
ver += ".dev{}".format(self.dev)

return ver


def parse_version(ver, pre=False):
"""Parse version into a comparable Version tuple."""

m = RE_VER.match(ver)

# Handle major, minor, micro
major = int(m.group('major'))
minor = int(m.group('minor')) if m.group('minor') else 0
micro = int(m.group('micro')) if m.group('micro') else 0

# Handle pre releases
if m.group('type'):
release = PRE_REL_MAP[m.group('type')]
pre = int(m.group('pre'))
else:
release = "final"
pre = 0

# Handle development releases
dev = m.group('dev') if m.group('dev') else 0
if m.group('dev'):
dev = int(m.group('dev'))
release = '.dev-' + release if pre else '.dev'
else:
dev = 0

# Handle post
post = int(m.group('post')) if m.group('post') else 0

return Version(major, minor, micro, release, pre, post, dev)


class Pep562(object):
"""
Backport of PEP 562 <https://pypi.org/search/?q=pep562>.
Wraps the module in a class that exposes the mechanics to override `__dir__` and `__getattr__`.
The given module will be searched for overrides of `__dir__` and `__getattr__` and use them when needed.
"""

def __init__(self, name):
"""Acquire `__getattr__` and `__dir__`, but only replace module for versions less than Python 3.7."""

self._module = sys.modules[name]
self._get_attr = getattr(self._module, '__getattr__', None)
self._get_dir = getattr(self._module, '__dir__', None)
sys.modules[name] = self

def __dir__(self):
"""Return the overridden `dir` if one was provided, else apply `dir` to the module."""

return self._get_dir() if self._get_dir else dir(self._module)

def __getattr__(self, name):
"""Attempt to retrieve the attribute from the module, and if missing, use the overridden function if present."""

try:
return getattr(self._module, name)
except AttributeError:
if self._get_attr:
return self._get_attr(name)
raise


__version_info__ = Version(1, 0, 0, "final")
__version__ = __version_info__._get_canonical()
39 changes: 1 addition & 38 deletions markdown/util.py
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Expand Up @@ -33,6 +33,7 @@
=============================================================================
"""
PY3 = sys.version_info[0] == 3
PY37 = (3, 7) <= sys.version_info

if PY3: # pragma: no cover
string_type = str
Expand Down Expand Up @@ -177,44 +178,6 @@ def code_escape(text):
"""


class ModuleWrap(object):
"""
Provided so that we can deprecate old version methodology.
See comments from Guido: <https://mail.python.org/pipermail/python-ideas/2012-May/014969.html>
and see PEP 562 which this is essentially a backport of: <https://www.python.org/dev/peps/pep-0562/>.
"""

def __init__(self, module):
"""Initialize."""

self._module = sys.modules[module]
sys.modules[module] = self

def __dir__(self):
"""
Implement the `dir` command.
Return module's results for the `dir` command along with any
attributes that have been added to the class.
"""

attr = (
set(dir(super(ModuleWrap, self).__getattribute__('_module'))) |
(set(self.__class__.__dict__.keys()) - set(ModuleWrap.__dict__.keys()))
)

return sorted(list(attr))

def __getattribute__(self, name):
"""Get the class attribute first and fallback to the module if not available."""

try:
return super(ModuleWrap, self).__getattribute__(name)
except AttributeError:
return getattr(super(ModuleWrap, self).__getattribute__('_module'), name)


class AtomicString(text_type):
"""A string which should not be further processed."""
pass
Expand Down
4 changes: 2 additions & 2 deletions tests/test_apis.py
Original file line number Diff line number Diff line change
Expand Up @@ -1039,7 +1039,7 @@ def test_deprecation_wrapper_dir(self):
"""Tests the `__dir__` attribute of the class as it replaces the module's."""

dir_attr = dir(markdown)
self.assertTrue('version' in dir_attr)
self.assertFalse('version' in dir_attr)
self.assertTrue('__version__' in dir_attr)
self.assertTrue('version_info' in dir_attr)
self.assertFalse('version_info' in dir_attr)
self.assertTrue('__version_info__' in dir_attr)
1 change: 1 addition & 0 deletions tox.ini
Original file line number Diff line number Diff line change
Expand Up @@ -21,3 +21,4 @@ commands = {toxinidir}/checkspelling.sh

[flake8]
max-line-length = 119
exclude=markdown/pep562.py

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