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Various tools for working with objects and classes in Python

Project description

Various tools for working with objects and classes in Python

Cached properties

Works just like a normal property, but returned values are cached:

from objecttools import CachedProperty

class ExpensiveOperations(object):
    def expensive_attribute(self):
        return self.calculate()

    # To make it settable

    def expensive_attribute(self, value):

    # To make it deletable

    def expensive_attribute(self):

e = ExpensiveOperations()
e.other_attribute = 1
print(e.expensive_attribute)  # Takes a long time.
print(e.expensive_attribute)  # Very quick; just retrieve from cache
v = e.expensive_attribute

e.other_attribute = 2  # expensive_attribute should be different now!
print(e.expensive_attribute)  # Old value that is wrong.
del e.expensive_attribute
print(e.expensive_attribute)  # Takes a long time, but returns new value.
e.other_attribute = 1
# Reset to known value
e.expensive_attribute = v
print(e.expensive_attribute)  # Correct value!


from objecttools import Singleton

Sentinel = Singleton.create('Sentinel')

Sentinel() is Sentinel()  # True

d.get('missing_value', Sentinel()) is Sentinel()  # True

class GlobalState(dict, metaclass=Singleton):
    attr = 0

gs = GlobalState()
gs['value'] = 7
gs.attr = 1

print(GlobalState()['value'] + GlobalState().attr)  # 8

For Python 2 and 3 compatibility, use it as a decorator:

class Class(object):


From PyPI

$ pip install objecttools

From source

$ git clone ''
$ python ./objecttools/ install

Project details

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