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  • Committer: glyph
  • Date: 2005-07-28 22:09:16 UTC
  • Revision ID: svn-v4:866e43f7-fbfc-0310-8f2a-ec88d1da2979:trunk:2
move this repository to a more official-looking URL

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Axiom/axiom/upgrade.py
 
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# -*- axiom.test.test_upgrading -*-
 
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_upgradeRegistry = {}
 
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def registerUpgrader(upgrader, typeName, oldVersion, newVersion):
 
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    """
 
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    Register a callable which can perform a schema upgrade between two
 
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    particular versions.
 
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    @param upgrader: A one-argument callable which will upgrade an object.  It
 
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    is invoked with an instance of the old version of the object.
 
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    @param typeName: The database typename for which this is an upgrader.
 
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    @param oldVersion: The version from which this will upgrade.
 
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    @param newVersion: The version tow hich this will upgrade.  This must be
 
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    exactly one greater than C{oldVersion}.
 
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    """
 
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    # assert (typeName, oldVersion, newVersion) not in _upgradeRegistry, "duplicate upgrader"
 
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    # ^ this makes the tests blow up so it's just disabled for now; perhaps we
 
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    # should have a specific test mode
 
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    assert newVersion - oldVersion == 1, "read the doc string"
 
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    _upgradeRegistry[typeName, oldVersion, newVersion] = upgrader
 
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def upgradeAllTheWay(o, typeName, version):
 
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    while True:
 
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        try:
 
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            upgrader = _upgradeRegistry[typeName, version, version + 1]
 
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        except KeyError:
 
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            break
 
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        else:
 
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            o = upgrader(o)
 
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            version += 1
 
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    return o