The standard correctly defines the return type of an assignment operator. Actually, the assignment operation itself doesn’t depend on the return value – that’s why the return type isn’t straightforward to understanding. The return type is important for chaining operations. Consider the following construction: a = b = c;. This should be equal to a …
When you say let 5 = 10 it’s not a redefinition of 5, it’s a pattern matching, the same which occurs when you say foo 5 = undefined … foo 10 … The pattern simply fails if it’s ever matched. In let-expressions the match is lazy. This means the match is only being done when …
Your code causes undefined behavior. Not just “undefined if A is used as a base class and this, that or the other”. Actually undefined, always. return *this is already UB, because this is not guaranteed to refer to the new object. Specifically, consider 3.8/7: If, after the lifetime of an object has ended and before …
A question that’s of greater importance in this case would be: “What does it mean, when a you write function in a way, that requires you to check for self assignment???” To answer my rhetorical question: It means that a well-designed assignment operator should not need to check for self-assignment. Assigning an object to itself …
One use case is the singleton pattern where there can only be exactly one instance of a class. In this case, you need make your constructors and assignment operator= private so that there is no way of creating more than one object. The only way to create an object is via your GetInstance() function as …
In PL/PgSQL parser, assignment operator is defined as assign_operator : ‘=’ | COLON_EQUALS ; This is a legacy feature, present in source code since 1998, when it was introduced – as we can see in the PostgreSQL Git repo. Starting from version 9.4 it is oficially documented. This idiosyncrasy – of having two operators for …
It’s part of a feature allowing C++11 non-static member functions to differentiate between whether they are being called on an lvalues or rvalues. In the above case, the copy assignment operator being defaulted here can only be called on lvalues. This uses the rules for lvalue and rvalue reference bindings that are well established; this …
The assignment operator in Java evaluates to the assigned value (like it does in, e.g., c). So here, readLine() will be executed, and its return value stored in line. That stored value is then checked against null, and if it’s null then the loop will terminate.