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Why is the order in dictionaries and sets arbitrary?
...ash tables, so there's still some liberty). The fact that dictionaries use __hash__ and __eq__ (and nothing else) is practically a language guarantee, not an implementation detail.
– user395760
Mar 18 '13 at 15:16
...
How to “perfectly” override a dict?
...bitrary key-altering
function before accessing the keys"""
def __init__(self, *args, **kwargs):
self.store = dict()
self.update(dict(*args, **kwargs)) # use the free update to set keys
def __getitem__(self, key):
return self.store[self.__keytransform__(key)]...
Why is __init__() always called after __new__()?
...
Use __new__ when you need to control
the creation of a new instance.
Use
__init__ when you need to control initialization of a new instance.
__new__ is the first step of instance creation. It's called first, and i...
How can I use mySQL replace() to replace strings in multiple records?
...
answered Dec 15 '15 at 21:06
Gianluca D'ArdiaGianluca D'Ardia
14411 silver badge99 bronze badges
...
Python read-only property
...he new-style classes.
Example:
>>> class A(object):
... def __init__(self, a):
... self._a = a
...
... @property
... def a(self):
... return self._a
...
>>> a = A('test')
>>> a.a
'test'
>>> a.a = 'pleh'
Traceback (most recent call la...
Calling parent class __init__ with multiple inheritance, what's the right way?
...s to greater flexibility for subclasses.
In the direct call approach, C.__init__ can call both A.__init__ and B.__init__.
When using super(), the classes need to be designed for cooperative multiple inheritance where C calls super, which invokes A's code which will also call super which invokes ...
Understanding __get__ and __set__ and Python descriptors
... how Python's property type is implemented. A descriptor simply implements __get__, __set__, etc. and is then added to another class in its definition (as you did above with the Temperature class). For example:
temp=Temperature()
temp.celsius #calls celsius.__get__
Accessing the property you assi...
How to make an immutable object in Python?
...utable object in Python could be slightly tricky. You can't just override __setattr__ , because then you can't even set attributes in the __init__ . Subclassing a tuple is a trick that works:
...
Python __str__ versus __unicode__
Is there a python convention for when you should implement __str__() versus __unicode__() . I've seen classes override __unicode__() more frequently than __str__() but it doesn't appear to be consistent. Are there specific rules when it is better to implement one versus the other? Is it ne...
How to override the copy/deepcopy operations for a Python object?
...ully, but this is the first time I've actually gone about overloading the __copy__ and __deepcopy__ methods. I've already Googled around and looked through the built-in Python modules to look for instances of the __copy__ and __deepcopy__ functions (e.g. sets.py , decimal.py , and fracti...