mar18_why_const.md

Const Means...

• don't touch my stuff
• I won't touch your stuff
• this doesn't change any stuff

---

Don't touch my stuff

// here's access to my rect, look, but don't modify it
Rect const & viewOfRect();

I won't touch your stuff

// give me your rect, I promise to only look at it, not modify it
void lookRect(Rect const & rc);

This doesn't change any stuff

struct Rect
{
   int area() const;  // this doesn't change Rect
   ...
};

---

Const means

Since most bugs are caused by state that has changed, const means

the bug is probably not here. Go look somewhere else.