Affector pattern for setting particular flag/mode for scope through lambdas

I need some pattern or rather proper name for next thing. I'm pretty sure it's not new, but I'd just suffered fiasco looking it in nets.

I need to setup and then relax some mode automatically by the end of function.

I provide lambdas for 'setup' and 'relax' actions into special 'Affector' object (or whatever name it has).

• First one is called during construction,
• and the second is called during destruction.

Thus even if I have an exception, or place 'return' statement somewhere in the middle, I still can be sure, that mode will be relaxed afterall.

Here is example of 'affector' thing:

class Affector {
public:
    Affector(
            std::function<void()> affect,
            std::function<void()> relax
            ) : Relax(relax) {
      affect();
    };

    ~Affector() { Relax(); }
protected:
    std::function<void()> Relax;
};

Example of use:

void Foo(MyObject *obj) {

     // During construction 'affector' sets 'some' mode,
     // we want to relax by the end of Foo.
     Affector affector(
                  [obj] { obj->setSomeMode(true); },
                  [obj] { obj->setSomeMode(false); }
              );

     obj->doSomething();

     // Here 'affector' relaxes 'some' mode during its destruction stage.
}