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README  view on Meta::CPAN

    Syntax of this file was designed to accomplish several goals:

      * Be able to automatically make sure each 'upgrade' operation has
      corresponding 'downgrade' operation (so it won't be forget - but, of
      course, it's impossible to automatically check is 'downgrade'
      operation will correctly undo effect of 'upgrade' operation).

      Thus custom file format is needed.

      * Make it easier to manually analyse is 'downgrade' operation looks
      correct for corresponding 'upgrade' operation.

      Thus related 'upgrade' and 'downgrade' operations must go one right
      after another.

      * Make it obvious some version can't be downgraded and have to be
      restored from backup.

      Thus RESTORE operation is named in upper case.

lib/App/migrate.pm  view on Meta::CPAN

Be able to automatically make sure each 'upgrade' operation has
corresponding 'downgrade' operation (so it won't be forget - but, of
course, it's impossible to automatically check is 'downgrade' operation
will correctly undo effect of 'upgrade' operation).

I<Thus custom file format is needed.>

=item *

Make it easier to manually analyse is 'downgrade' operation looks correct
for corresponding 'upgrade' operation.

I<Thus related 'upgrade' and 'downgrade' operations must go one right
after another.>

=item *

Make it obvious some version can't be downgraded and have to be restored
from backup.