BASIC IDEA: Using this class as a base class, you can quickly create new classes that know what its attributes are. This is useful for simple, struct-like classes that have no methods of their own. Afterall, class syntax is more convenient than dict syntax.
Python, 63 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 | """This file contains the AutomaticClass class."""
class AutomaticClass:
"""This is a base class for simple, struct-like classes."""
def __init__(self, **kargs):
"""Subclasses should call this after initializing any defaults.
**kargs - Set each attribute with the given value. Keys in kargs that
aren't in self.__attributes__ will be ignored.
"""
for i in self.__attributes__:
if kargs.has_key(i):
setattr(self, i, kargs[i])
def getAttributes(self):
"""Return the list of attributes that this class uses.
Subclasses should extend (not override) this method to add their own
attributes.
"""
return []
def __getattr__(self, attribute):
"""Handle the following attributes manually: __attributes__.
Meta, meta, meta!
"""
if attribute == "__attributes__":
return self.getAttributes()
raise AttributeError
def __repr__(self):
"""Return a suitable string representing of this instance."""
attributes = []
for i in self.__attributes__:
try:
value = getattr(self, i)
except:
value = "Undefined"
attributes.append("%s=%s" % (i, value))
return "<%s %s>" % (self.__class__.__name__, " ".join(attributes))
# This is for testing.
class _Test(AutomaticClass):
def __init__(self, **kargs):
self.foo = "Bar"
AutomaticClass.__init__(self, **kargs)
def getAttributes(self):
return AutomaticClass.getAttributes(self) + ["foo"]
# Do some testing.
if __name__ == '__main__':
assert `_Test()` == "<_Test foo=Bar>"
assert _Test().foo == "Bar"
assert _Test(foo = "Not bar").foo == "Not bar"
|
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