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
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
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
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
Once the anonymous class instance has been implicitly cast into the named type it can’t be cast back because there is no name for the anonymous type. You can access the additional members of the anonymous inner class through this within the class, in the expression immediate after the expression and the type can be … Read more
You need to call a(int) explicitly in the constructor initializer list: b() : aInstance(3) {} Where 3 is the initial value you’d like to use. Though it could be any int. See comments for important notes on order and other caveats.
If you have only one instance anyway, it’s best to make all variables per-instance, simply because they will be accessed (a little bit) faster (one less level of “lookup” due to the “inheritance” from class to instance), and there are no downsides to weigh against this small advantage.
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
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
It’s 0. It can’t be null, as null isn’t a valid int value. From section 7.6.10.4 of the C# 5 specification: All elements of the new array instance are initialized to their default values (§5.2). And from section 5.2: The default value of a variable depends on the type of the variable and is determined … Read more