Ref-qualifiers – introduced in C++11 Ref-qualifiers is not C++17 feature (looking at the tag of the question), but was a feature introduced in C++11. struct Foo { void bar() const & { std::cout << “const lvalue Foo\n”; } void bar() & { std::cout << “lvalue Foo\n”; } void bar() const && { std::cout << “const … Read more
You want this: typedef void (K::*MemFuncType)() const; If you want to still base MemFuncType on FuncType, you need to change FuncType: typedef void FuncType() const; typedef FuncType K::* MemFuncType;
If you have two overloads that differ only in their const-ness, then the compiler resolves the call based on whether *this is const or not. In your example code, test is not const, so the non-const overload is called. If you did this: testType test; const testType &test2 = test; test2->x(); you should see that … Read more
Just read down below: During overload resolution, non-static cv-qualified member function of class X is treated as a function that takes an implicit parameter of type lvalue reference to cv-qualified X if it has no ref-qualifiers or if it has the lvalue ref-qualifier. Otherwise (if it has rvalue ref-qualifier), it is treated as a function … Read more
What can a ‘const’ method change? Without explicitly casting away constness, a const member function can change: mutable data members, and any data the class has non-const access to, irrespective of whether that data’s accessible: via member variables that are pointers or references, via pointers or references passed as function arguments, via pointers or references … Read more
The objects in the std::set are stored as const StudentT. So when you try to call getId() with the const object the compiler detects a problem, mainly you’re calling a non-const member function on const object which is not allowed because non-const member functions make NO PROMISE not to modify the object; so the compiler … Read more
When you apply the const qualifier to a nonstatic member function, it affects the this pointer. For a const-qualified member function of class C, the this pointer is of type C const*, whereas for a member function that is not const-qualified, the this pointer is of type C*. A static member function does not have … Read more
When you call a.foo();, the compiler goes through overload resolution to find the best function to use. When it builds the overload set it finds void foo() const and void foo() Now, since a is not const, the non-const version is the best match, so the compiler picks void foo(). Then the access restrictions are … Read more