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138
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1 #!/usr/bin/env python
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2
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3 """
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4 illustrates usage of the undefined pattern from e.g.
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5 http://k0s.org/mozilla/hg/bzconsole/file/tip/bzconsole/command.py
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6
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7 This is useful for scenarios similar to:
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8 - you have base configuration in a file
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9 - you have an OptionParser to read options in the command line
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10 - the CLI options should overwrite the file configuration iff
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11 the user specifies an option
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12 """
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13
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14 from optparse import OptionParser
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15
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16 class Undefined(object):
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17 def __init__(self, default):
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18 self.default=default
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19
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20 class UndefinedOptionParser(OptionParser):
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21
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22 def add_option(self, *args, **kwargs):
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23 kwargs['default'] = Undefined(kwargs.get('default'))
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24 OptionParser.add_option(self, *args, **kwargs)
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25
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26 def parse_args(self, *args, **kwargs):
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27 options, args = OptionParser.parse_args(self, *args, **kwargs)
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28 return options, args
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29
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30 if __name__ == '__main__':
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31
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32 myparser = UndefinedOptionParser()
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33 myparser.add_option("--foo", dest='foo', default='hello')
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34 myparser.add_option("--bar", dest='bar', default='goodbye')
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35 myparser.add_option("--baz", dest='baz', default='helloagain')
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36 myparser.add_option("--fleem", dest='fleem', default='aufwiedersehen')
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37
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38 myconfiguration = {'foo': 'hi',
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39 'bar': 'ciao'}
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40 options, args = myparser.parse_args(['--foo', 'hello', '--baz', 'hola'])
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41 for key, value in options.__dict__.items():
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42 # XXX ideally you would move this to parse_args
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43 if isinstance(value, Undefined):
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44 options.__dict__[key] = myconfiguration.get(key, value.default)
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45
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46 assert options.foo == 'hello'
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47 assert options.bar == 'ciao'
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48 assert options.baz == 'hola'
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49 assert options.fleem == 'aufwiedersehen'
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