Here is some error with my .h file which show [Error] unterminated #ifndef when I include my class template in it
You need to add a #endif to the end of your header file.
inheritance
Preventing a Java class from being instantiated and inherited
A class can’t be both final and abstract. You can prevent instantiation by hiding the constructor, and raising an exception to prevent instantiation via reflection. That looks like this:
C++ calling base class constructors
The short answer for this is, “because that’s what the C++ standard specifies”. Note that you can always specify a constructor that’s different from the default, like so: The default constructor of the base class is called only if you don’t specify which one to call.
Struct inheritance in C++
Can a struct be inherited in C++?
TypeError: module.__init__() takes at most 2 arguments (3 given)
Your error is happening because Object is a module, not a class. So your inheritance is screwy. Change your import statement to: and your class definition to: or change your class definition to:
What’s wrong with overridable method calls in constructors?
On invoking overridable method from constructors Simply put, this is wrong because it unnecessarily opens up possibilities to MANY bugs. When the @Override is invoked, the state of the object may be inconsistent and/or incomplete. A quote from Effective Java 2nd Edition, Item 17: Design and document for inheritance, or else prohibit it: There are … Read more
Inheritance vs. Aggregation [closed]
It’s not a matter of which is the best, but of when to use what. In the ‘normal’ cases a simple question is enough to find out if we need inheritance or aggregation. If The new class is more or less as the original class. Use inheritance. The new class is now a subclass of … Read more
Why is there no multiple inheritance in Java, but implementing multiple interfaces is allowed?
Because interfaces specify only what the class is doing, not how it is doing it. The problem with multiple inheritance is that two classes may define different ways of doing the same thing, and the subclass can’t choose which one to pick.
Inheritance and init method in Python
In the first situation, Num2 is extending the class Num and since you are not redefining the special method named __init__() in Num2, it gets inherited from Num. When a class defines an __init__() method, class instantiation automatically invokes __init__() for the newly-created class instance. In the second situation, since you are redefining __init__() in Num2 you need to explicitly call the one in the super class (Num) if you want … Read more
Ruby: kind_of? vs. instance_of? vs. is_a?
kind_of? and is_a? are synonymous. instance_of? is different from the other two in that it only returns true if the object is an instance of that exact class, not a subclass. Example: “hello”.is_a? Object and “hello”.kind_of? Object return true because “hello” is a String and String is a subclass of Object. However “hello”.instance_of? Object returns … Read more