Suppose I have a class Foo, with a private variable bar_ containing some state for Foo. If necessary, I may write public get/set metho         
        
If your compiler does any inlining at all, it will be able to inline get and set methods defined and used within a given class.  const has no bearing on this, and the inline directive doesn't make much difference either.
I generally prefer to use my get() and set() methods even from within the class definition, when I can.  You get all the same benefits that you get by using them outside the class definition, and there is no speed penalty.