Here, i’m creating instance of my class No, you are not creating the instance of your abstract class here. Rather you are creating an instance of an anonymous subclass of your abstract class. And then you are invoking the method on your abstract class reference pointing to subclass object. This behaviour is clearly listed in … Read more
C++ has two kinds of enum: enum classes Plain enums Here are a couple of examples on how to declare them: enum class Color { red, green, blue }; // enum class enum Animal { dog, cat, bird, human }; // plain enum What is the difference between the two? enum classes – enumerator names … Read more
I wrote my thoughts of static classes in an earlier Stack Overflow answer: Class with single method — best approach? I used to love utility classes filled up with static methods. They made a great consolidation of helper methods that would otherwise lie around causing redundancy and maintenance hell. They’re very easy to use, no … Read more
Here’s the way to do it without using any external libraries: // Define a class like this function Person(name, gender){ // Add object properties like this this.name = name; this.gender = gender; } // Add methods like this. All Person objects will be able to invoke this Person.prototype.speak = function(){ alert(“Howdy, my name is” + … Read more
It’s cultural. In Python, you don’t write to other classes’ instance or class variables. In Java, nothing prevents you from doing the same if you really want to – after all, you can always edit the source of the class itself to achieve the same effect. Python drops that pretence of security and encourages programmers … Read more
The first is used to initialise newly created object, and receives arguments used to do that: class Foo: def __init__(self, a, b, c): # … x = Foo(1, 2, 3) # __init__ The second implements function call operator. class Foo: def __call__(self, a, b, c): # … x = Foo() x(1, 2, 3) # __call__
tl;dr class C defines a class, just as in Java or C++. object O creates a singleton object O as instance of some anonymous class; it can be used to hold static members that are not associated with instances of some class. object O extends T makes the object O an instance of trait T; … Read more
>>> class Test: … def __repr__(self): … return “Test()” … def __str__(self): … return “member of Test” … >>> t = Test() >>> t Test() >>> print(t) member of Test The __str__ method is what gets called happens when you print it, and the __repr__ method is what happens when you use the repr() function … Read more
Use the super() function: class Foo(Bar): def baz(self, **kwargs): return super().baz(**kwargs) For Python < 3, you must explicitly opt in to using new-style classes and use: class Foo(Bar): def baz(self, arg): return super(Foo, self).baz(arg)
In .NET, there are two categories of types, reference types and value types. Structs are value types and classes are reference types. The general difference is that a reference type lives on the heap, and a value type lives inline, that is, wherever it is your variable or field is defined. A variable containing a … Read more