Useful class and decorator for create immutable objects. Decorator mutablemethod used for define mutable methods.
Python, 48 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 | class Immutable(object):
"""An immutable class.
"""
_mutable = False
def __setattr__(self, name,value):
if self._mutable or name == '_mutable':
super(Immutable,self).__setattr__(name,value)
else:
raise TypeError("Can't modify immutable instance")
def __delattr__(self,name):
if self._mutable:
super(Immutable,self).__delattr__(name)
else:
raise TypeError("Can't modify immutable instance")
def mutablemethod(f):
def func(self,*args, **kwargs):
if isinstance(self,Immutable):
old_mutable = self._mutable
self._mutable = True
res = f(self,*args, **kwargs)
self._mutable = old_mutable
else:
res = f(self,*args, **kwargs)
return res
return func
if __name__ == '__main__':
class A(Immutable):
'''
Define __init__ can set attributes for instance
'''
@mutablemethod
def __init__(self,value):
super(A,self).__init__(self)
self.value = value
def try_change(self,value):
self.value = value
a = A("test")
a.try_change("TEST")
a.value = "TEST"
|
