92 lines
2.3 KiB
Python
92 lines
2.3 KiB
Python
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'''
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Dummy Class, intended as an abstract class for the creation
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of base/builtin classes with slightly altered functionality
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uses _base as the name of an instance of the base datatype,
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mapping all special functions to that name.
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>>> from mcf.utils import dummy
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>>> j = dummy.Dummy({})
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>>> j['this'] = 23
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>>> j
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{'this': 23}
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>>> class example(dummy.Dummy):
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... def __repr__(self):
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... return '<example: %s>'%`self._base`
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>>> k = example([])
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>>> k # uses the __repr__ function
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<example: []>
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>>> k.append # finds the attribute of the _base
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<built-in method append of list object at 501830>
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'''
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import types, copy
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class Dummy:
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'Abstract class for slightly altering functionality of objects (including builtins)'
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def __init__(self, val=None):
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'Initialisation, should be overridden'
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if val and type(val)== types.InstanceType and hasattr(val, '_base'):
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# Dict is used because subclasses often want to override
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# the setattr function
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self.__dict__['_base']=copy.copy(val.__dict__['_base'])
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else:
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self.__dict__['_base'] = val
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def __repr__(self):
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'Return a string representation'
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return repr(self._base)
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def __str__(self):
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'Convert to a string'
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return str(self._base)
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def __cmp__(self,other):
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'Compare to other value'
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# altered 98.03.17 from if...elif...else statement
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return cmp(self._base, other)
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def __getitem__(self, key):
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'Get an item by index'
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return self._base[key]
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def __setitem__(self, key, val):
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'Set an item by index'
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self._base[key]=val
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def __len__(self):
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'return the length of the self'
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return len(self._base)
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def __delitem__(self, key):
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'remove an item by index'
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del(self._base[key])
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def __getslice__(self, i, j):
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'retrieve a slice by indexes'
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return self._base[i:j]
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def __setslice__(self, i, j, val):
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'set a slice by indexes to values'
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self._base[i:j]=val
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def __delslice__(self, i, j):
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'remove a slice by indexes'
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del(self._base[i:j])
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def __nonzero__(self):
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if self._base:
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return 1
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else:
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return 0
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def __getattr__(self, attr):
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'find an attribute when normal lookup fails, will raise a KeyError if missing _base attribute'
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try:
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return getattr( self.__dict__['_base'], attr)
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except (AttributeError, KeyError):
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try:
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return self.__dict__['_base'][attr]
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except (KeyError,TypeError):
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pass
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raise AttributeError, attr
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