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How to make a class property? [duplicate]

...az.bar == 50 assert foo.bar == 50 The setter didn't work at the time we call Bar.bar, because we are calling TypeOfBar.bar.__set__, which is not Bar.bar.__set__. Adding a metaclass definition solves this: class ClassPropertyMetaClass(type): def __setattr__(self, key, value): if key ...
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Why is using 'eval' a bad practice?

...d eval have nothing to do with each other. An application that's fundamentally mis-designed is fundamentally mis-designed. eval is no more the root cause of bad design than division by zero or attempting to import a module which is known not to exist. eval isn't insecure. Applications are insecu...
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What __init__ and self do on Python?

...to declare it explicitly. When you create an instance of the A class and call its methods, it will be passed automatically, as in ... a = A() # We do not pass any argument to the __init__ method a.method_a('Sailor!') # We only pass a single argument The __init__ method is roughly w...
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How can I filter a date of a DateTimeField in Django?

... Much better than all of the other answers here, thanks! – Kin Jan 6 '14 at 17:06 ...
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How to add property to a class dynamically?

...ing on. Better late than never. You can add a property to a class dynamically. But that's the catch: you have to add it to the class. >>> class Foo(object): ... pass ... >>> foo = Foo() >>> foo.a = 3 >>> Foo.b = property(lambda self: self.a + 1) >>&...
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How can I implement a tree in Python?

... I came across this answer via Google. This library is really nice. I especially love the ability to use the mixin class to make an tree of any object! – Rÿck Nöthing Mar 8 '19 at 1:21 ...
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Get the latest record from mongodb collection

...1 means order opposite of the one that records are inserted in. Edit: For all the downvoters, above is a Mongoose syntax, mongo CLI syntax is: db.collectionName.find({}).sort({$natural:-1}).limit(1) share | ...
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Why is Python 3.x's super() magic?

In Python 3.x, super() can be called without arguments: 1 Answer 1 ...
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How can I add reflection to a C++ application?

...rate the data about each field(plus the field itself). This macro will be called like this: REFLECTABLE ( (const char *) name, (int) age ) So using Boost.PP we iterate over each argument and generate the data like this: // A helper metafunction for adding const to a type template<clas...
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Passing a 2D array to a C++ function

... @Zack: You're right, there're only really two cases; one is a pointer-to-pointer and other being a single pointer to an integer array of size n i.e. int (*a) [10]. – legends2k Jul 10 '13 at 10:44 ...