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# The SmartDict class fixes a couple of issues with using the content
# of os.environ or similar dicts of strings as Python variables:
#
# 1) Undefined variables should return False rather than raising KeyError.
#
# 2) String values of 'False', '0', etc., should evaluate to False
# (not just the empty string).
#
# #1 is solved by overriding __getitem__, and #2 is solved by using a
# proxy class for values and overriding __nonzero__ on the proxy.
# Everything else is just to (a) make proxies behave like normal
# values otherwise, (b) make sure any dict operation returns a proxy
# rather than a normal value, and (c) coerce values written to the
# dict to be strings.
from convert import *
class SmartDict(dict):
class Proxy(str):
def __int__(self):
return int(to_integer(str(self)))
def __long__(self):
return long(to_integer(str(self)))
def __float__(self):
return float(to_integer(str(self)))
def __nonzero__(self):
return to_bool(str(self))
def convert(self, other):
t = type(other)
if t == bool:
return bool(self)
if t == int:
return int(self)
if t == long:
return long(self)
if t == float:
return float(self)
return str(self)
def __lt__(self, other):
return self.convert(other) < other
def __le__(self, other):
return self.convert(other) <= other
def __eq__(self, other):
return self.convert(other) == other
def __ne__(self, other):
return self.convert(other) != other
def __gt__(self, other):
return self.convert(other) > other
def __ge__(self, other):
return self.convert(other) >= other
def __add__(self, other):
return self.convert(other) + other
def __sub__(self, other):
return self.convert(other) - other
def __mul__(self, other):
return self.convert(other) * other
def __div__(self, other):
return self.convert(other) / other
def __truediv__(self, other):
return self.convert(other) / other
def __radd__(self, other):
return other + self.convert(other)
def __rsub__(self, other):
return other - self.convert(other)
def __rmul__(self, other):
return other * self.convert(other)
def __rdiv__(self, other):
return other / self.convert(other)
def __rtruediv__(self, other):
return other / self.convert(other)
# __getitem__ uses dict.get() to return 'False' if the key is not
# found (rather than raising KeyError). Note that this does *not*
# set the key's value to 'False' in the dict, so that even after
# we call env['foo'] we still get a meaningful answer from "'foo'
# in env" (which calls dict.__contains__, which we do not
# override).
def __getitem__(self, key):
return self.Proxy(dict.get(self, key, 'False'))
def __setitem__(self, key, item):
dict.__setitem__(self, key, str(item))
def values(self):
return [ self.Proxy(v) for v in dict.values(self) ]
def itervalues(self):
for value in dict.itervalues(self):
yield self.Proxy(value)
def items(self):
return [ (k, self.Proxy(v)) for k,v in dict.items(self) ]
def iteritems(self):
for key,value in dict.iteritems(self):
yield key, self.Proxy(value)
def get(self, key, default='False'):
return self.Proxy(dict.get(self, key, str(default)))
def setdefault(self, key, default='False'):
return self.Proxy(dict.setdefault(self, key, str(default)))
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