244 lines
9.1 KiB
Python
244 lines
9.1 KiB
Python
"""Provides classes to represent module version numbers (one class for
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each style of version numbering). There are currently two such classes
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implemented: StrictVersion and LooseVersion.
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Every version number class implements the following interface:
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* the 'parse' method takes a string and parses it to some internal
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representation; if the string is an invalid version number,
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'parse' raises a ValueError exception
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* the class constructor takes an optional string argument which,
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if supplied, is passed to 'parse'
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* __str__ reconstructs the string that was passed to 'parse' (or
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an equivalent string -- ie. one that will generate an equivalent
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version number instance)
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* __repr__ generates Python code to recreate the version number instance
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* _cmp compares the current instance with either another instance
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of the same class or a string (which will be parsed to an instance
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of the same class, thus must follow the same rules)
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"""
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import re
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import sys
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# The rules according to Greg Stein:
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# 1) a version number has 1 or more numbers separated by a period or by
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# sequences of letters. If only periods, then these are compared
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# left-to-right to determine an ordering.
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# 2) sequences of letters are part of the tuple for comparison and are
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# compared lexicographically
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# 3) recognize the numeric components may have leading zeroes
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#
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# The LooseVersion class below implements these rules: a version number
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# string is split up into a tuple of integer and string components, and
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# comparison is a simple tuple comparison. This means that version
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# numbers behave in a predictable and obvious way, but a way that might
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# not necessarily be how people *want* version numbers to behave. There
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# wouldn't be a problem if people could stick to purely numeric version
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# numbers: just split on period and compare the numbers as tuples.
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# However, people insist on putting letters into their version numbers;
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# the most common purpose seems to be:
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# - indicating a "pre-release" version
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# ('alpha', 'beta', 'a', 'b', 'pre', 'p')
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# - indicating a post-release patch ('p', 'pl', 'patch')
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# but of course this can't cover all version number schemes, and there's
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# no way to know what a programmer means without asking him.
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#
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# The problem is what to do with letters (and other non-numeric
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# characters) in a version number. The current implementation does the
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# obvious and predictable thing: keep them as strings and compare
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# lexically within a tuple comparison. This has the desired effect if
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# an appended letter sequence implies something "post-release":
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# eg. "0.99" < "0.99pl14" < "1.0", and "5.001" < "5.001m" < "5.002".
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#
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# However, if letters in a version number imply a pre-release version,
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# the "obvious" thing isn't correct. Eg. you would expect that
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# "1.5.1" < "1.5.2a2" < "1.5.2", but under the tuple/lexical comparison
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# implemented here, this just isn't so.
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#
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# Two possible solutions come to mind. The first is to tie the
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# comparison algorithm to a particular set of semantic rules, as has
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# been done in the StrictVersion class above. This works great as long
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# as everyone can go along with bondage and discipline. Hopefully a
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# (large) subset of Python module programmers will agree that the
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# particular flavour of bondage and discipline provided by StrictVersion
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# provides enough benefit to be worth using, and will submit their
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# version numbering scheme to its domination. The free-thinking
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# anarchists in the lot will never give in, though, and something needs
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# to be done to accommodate them.
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#
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# Perhaps a "moderately strict" version class could be implemented that
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# lets almost anything slide (syntactically), and makes some heuristic
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# assumptions about non-digits in version number strings. This could
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# sink into special-case-hell, though; if I was as talented and
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# idiosyncratic as Larry Wall, I'd go ahead and implement a class that
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# somehow knows that "1.2.1" < "1.2.2a2" < "1.2.2" < "1.2.2pl3", and is
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# just as happy dealing with things like "2g6" and "1.13++". I don't
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# think I'm smart enough to do it right though.
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#
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# In any case, I've coded the test suite for this module (see
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# ../test/test_version.py) specifically to fail on things like comparing
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# "1.2a2" and "1.2". That's not because the *code* is doing anything
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# wrong, it's because the simple, obvious design doesn't match my
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# complicated, hairy expectations for real-world version numbers. It
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# would be a snap to fix the test suite to say, "Yep, LooseVersion does
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# the Right Thing" (ie. the code matches the conception). But I'd rather
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# have a conception that matches common notions about version numbers.
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if sys.version_info >= (3,):
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class _Py2Int(int):
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"""Integer object that compares < any string"""
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def __gt__(self, other):
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if isinstance(other, str):
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return False
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return super().__gt__(other)
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def __lt__(self, other):
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if isinstance(other, str):
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return True
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return super().__lt__(other)
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else:
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_Py2Int = int
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class LooseVersion(object):
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"""Version numbering for anarchists and software realists.
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Implements the standard interface for version number classes as
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described above. A version number consists of a series of numbers,
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separated by either periods or strings of letters. When comparing
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version numbers, the numeric components will be compared
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numerically, and the alphabetic components lexically. The following
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are all valid version numbers, in no particular order:
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1.5.1
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1.5.2b2
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161
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3.10a
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8.02
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3.4j
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1996.07.12
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3.2.pl0
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3.1.1.6
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2g6
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11g
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0.960923
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2.2beta29
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1.13++
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5.5.kw
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2.0b1pl0
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In fact, there is no such thing as an invalid version number under
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this scheme; the rules for comparison are simple and predictable,
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but may not always give the results you want (for some definition
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of "want").
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"""
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component_re = re.compile(r"(\d+ | [a-z]+ | \.)", re.VERBOSE)
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def __init__(self, vstring=None):
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if vstring:
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self.parse(vstring)
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def __eq__(self, other):
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c = self._cmp(other)
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if c is NotImplemented:
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return NotImplemented
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return c == 0
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def __lt__(self, other):
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c = self._cmp(other)
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if c is NotImplemented:
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return NotImplemented
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return c < 0
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def __le__(self, other):
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c = self._cmp(other)
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if c is NotImplemented:
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return NotImplemented
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return c <= 0
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def __gt__(self, other):
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c = self._cmp(other)
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if c is NotImplemented:
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return NotImplemented
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return c > 0
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def __ge__(self, other):
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c = self._cmp(other)
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if c is NotImplemented:
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return NotImplemented
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return c >= 0
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def parse(self, vstring):
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# I've given up on thinking I can reconstruct the version string
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# from the parsed tuple -- so I just store the string here for
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# use by __str__
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self.vstring = vstring
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components = [x for x in self.component_re.split(vstring) if x and x != "."]
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for i, obj in enumerate(components):
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try:
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components[i] = int(obj)
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except ValueError:
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pass
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self.version = components
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def __str__(self):
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return self.vstring
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def __repr__(self):
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return "LooseVersion ('%s')" % str(self)
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def _cmp(self, other):
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other = self._coerce(other)
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if other is NotImplemented:
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return NotImplemented
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if self.version == other.version:
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return 0
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if self.version < other.version:
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return -1
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if self.version > other.version:
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return 1
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return NotImplemented
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@classmethod
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def _coerce(cls, other):
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if isinstance(other, cls):
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return other
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elif isinstance(other, str):
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return cls(other)
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elif "distutils" in sys.modules:
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# Using this check to avoid importing distutils and suppressing the warning
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try:
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from distutils.version import LooseVersion as deprecated
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except ImportError:
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return NotImplemented
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if isinstance(other, deprecated):
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return cls(str(other))
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return NotImplemented
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class LooseVersion2(LooseVersion):
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"""LooseVersion variant that restores Python 2 semantics
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In Python 2, comparing LooseVersions where paired components could be string
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and int always resulted in the string being "greater". In Python 3, this produced
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a TypeError.
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"""
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def parse(self, vstring):
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# I've given up on thinking I can reconstruct the version string
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# from the parsed tuple -- so I just store the string here for
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# use by __str__
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self.vstring = vstring
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components = [x for x in self.component_re.split(vstring) if x and x != "."]
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for i, obj in enumerate(components):
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try:
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components[i] = _Py2Int(obj)
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except ValueError:
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pass
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self.version = components
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