This question got me thinking about bare strings.

When PHP sees a string that's not enclosed in quotes, it first checks to see if it's a constant. If not, it just assumes it's a string and goes on anyway. So for example if I have

echo $foo[bar];

If there's a constant called bar it uses that for the array key, but if not then it treats bar as a bare string, so it behaves just like

echo $foo["bar"];

This can cause all kinds of problems if at some future date a constant is added with the same name.

My question is, is there any situation in which it actually makes sense to use a bare string?