I wouldn't want SafeString is-a String, I would want a conversion from SafeString to String that removes whatever encoding or escaping was applied. Otherwise yo

I wouldn't want SafeString is-a String, I would want a conversion from SafeString to String that removes whatever encoding or escaping was applied. Otherwise you end up re-encoding values that unbeknownst to you don't need it, which is why there are thousands of terrible PHP bulletin boards out there which won't let you use quotes without mangling them.