member

php static function

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In the first class, sayHi() is actually an instance method which you are calling as a static method and you get away with it because sayHi() never refers to $this. Static functions are associated with the class, not an instance of the class. As such, $this is not available from a static context ($this isn’t … Read more

Why I can access member functions even after the object was deleted?

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So, my question is, why I’m still able to call Go_XXX_Your_Self() and Identify_Your_Self() even after the object was deleted? Because of undefined behavior. Is this how it works in C++? (is there even after you delete it?) Because of undefined behavior. There is no guarantee that it will work the same on other implementations. Again, … Read more

“No appropriate default constructor available”–Why is the default constructor even called?

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Your default constructor is implicitly called here: ProxyPiece::ProxyPiece(CubeGeometry& c) { cube=c; } You want ProxyPiece::ProxyPiece(CubeGeometry& c) :cube(c) { } Otherwise your ctor is equivalent to ProxyPiece::ProxyPiece(CubeGeometry& c) :cube() //default ctor called here! { cube.operator=(c); //a function call on an already initialized object } The thing after the colon is called a member initialization list. Incidentally, … Read more

C++ static template member, one instance for each template type?

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Static members are different for each diffrent template initialization. This is because each template initialization is a different class that is generated by the compiler the first time it encounters that specific initialization of the template. The fact that static member variables are different is shown by this code: #include <iostream> template <class T> class … Read more

How can I declare a member vector of the same class?

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This paper was adopted into C++17 which allows incomplete types to be used in certain STL containers. Prior to that, it was Undefined Behavior. To quote from the paper: Based on the discussion on the Issaquah meeting, we achieved the consensus to proceed* with the approach – “Containers of Incomplete Types”, but limit the scope … Read more

class variables is shared across all instances in python? [duplicate]

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var should definitely not be shared as long as you access it by instance.var or self.var. With the list however, what your statement does is when the class gets evaluated, one list instance is created and bound to the class dict, hence all instances will have the same list. Whenever you set instance.list = somethingelse … Read more