view roundup/anypy/cmp_.py @ 5525:bb7865241f8a

Make CSV import/export compatible across Python versions (also RDBMS journals) (issue 2550976, issue 2550975). The roundup-admin export and import commands are used for migrating between different database backends. It is desirable that they should be usable also for migrations between Python 2 and Python 3, and in some cases (e.g. with the anydbm backend) this may be required. To be usable for such migrations, the format of the generated CSV files needs to be stable, meaning the same as currently used with Python 2. The export process uses repr() to produce the fields in the CSV files and eval() to convert them back to Python data structures. repr() of strings with non-ASCII characters produces different results for Python 2 and Python 3. This patch adds repr_export and eval_import functions to roundup/anypy/strings.py which provide the required operations that are just repr() and eval() in Python 2, but are more complicated in Python 3 to use data representations compatible with Python 2. These functions are then used in the required places for export and import. repr() and eval() are also used in storing the dict of changed values in the journal for the RDBMS backends. It is similarly desirable that the database be compatible between Python 2 and Python 3, so that export and import do not need to be used for a migration between Python versions for non-anydbm back ends. Thus, this patch changes rdbms_common.py in the places involved in storing journals in the database, not just in those involved in import/export. Given this patch, import/export with non-ASCII characters appear based on some limited testing to work across Python versions, and an instance using the sqlite backend appears to be compatible between Python versions without needing import/export, *if* the sessions/otks databases (which use anydbm) are deleted when changing Python version.
author Joseph Myers <jsm@polyomino.org.uk>
date Sun, 02 Sep 2018 23:48:04 +0000
parents 9a09719b0d8e
children 142553f58694
line wrap: on
line source

try:
    None < 0
    def NoneAndDictComparable(v):
        return v
except TypeError:
    # comparator to allow comparisons against None and dict
    # comparisons (these were allowed in Python 2, but aren't allowed
    # in Python 3 any more)
    class NoneAndDictComparable(object):
        def __init__(self, value):
            self.value = value

        def __cmp__(self, other):
            if not isinstance(other, self.__class__):
                raise TypeError('not comparable')

            if self.value == other.value:
                return 0

            elif self.value is None:
                return -1

            elif other.value is None:
                return 1

            elif type(self.value) == tuple and type(other.value) == tuple:
                for lhs, rhs in zip(self.value, other.value):
                    lhsCmp = NoneAndDictComparable(lhs)
                    rhsCmp = NoneAndDictComparable(rhs)
                    result = lhsCmp.__cmp__(rhsCmp)
                    if result != 0:
                        return result

                return len(self.value) - len(other.value)

            elif type(self.value) == dict and type(other.value) == dict:
                diff = len(self.value) - len(other.value)
                if diff == 0:
                    lhsItems = tuple(sorted(self.value.items(),
                                            key=NoneAndDictComparable))
                    rhsItems = tuple(sorted(other.value.items(),
                                            key=NoneAndDictComparable))
                    return -1 if NoneAndDictComparable(lhsItems) < NoneAndDictComparable(rhsItems) else 1
                else:
                    return diff

            elif self.value < other.value:
                return -1

            else:
                return 1

        def __eq__(self, other):
            return self.__cmp__(other) == 0
        def __ne__(self, other):
            return self.__cmp__(other) != 0
        def __lt__(self, other):
            return self.__cmp__(other) < 0
        def __le__(self, other):
            return self.__cmp__(other) <= 0
        def __ge__(self, other):
            return self.__cmp__(other) >= 0
        def __gt__(self, other):
            return self.__cmp__(other) > 0

def _test():
    Comp = NoneAndDictComparable

    assert Comp(None) < Comp(0)
    assert Comp(None) < Comp('')
    assert Comp(None) < Comp({})
    assert Comp((0, None)) < Comp((0, 0))
    assert not Comp(0) < Comp(None)
    assert not Comp('') < Comp(None)
    assert not Comp({}) < Comp(None)
    assert not Comp((0, 0)) < Comp((0, None))

    assert Comp((0, 0)) < Comp((0, 0, None))
    assert Comp((0, None, None)) < Comp((0, 0, 0))

    assert Comp(0) < Comp(1)
    assert Comp(1) > Comp(0)
    assert not Comp(1) < Comp(0)
    assert not Comp(0) > Comp(0)

    assert Comp({ 0: None }) < Comp({ 0: 0 })
    assert Comp({ 0: 0 }) < Comp({ 0: 1 })

    assert Comp({ 0: 0 }) == Comp({ 0: 0 })
    assert Comp({ 0: 0 }) != Comp({ 0: 1 })
    assert Comp({ 0: 0, 1: 1 }) > Comp({ 0: 1 })
    assert Comp({ 0: 0, 1: 1 }) < Comp({ 0: 0, 2: 2 })

if __name__ == '__main__':
    _test()

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