At Sat, 22 Jan 2011 03:40:44 +0800, Dean Michael Berris wrote:
On Sat, Jan 22, 2011 at 3:18 AM, Dave Abrahams <dave@boostpro.com> wrote:
At Sat, 22 Jan 2011 01:56:36 +0800, Dean Michael Berris wrote:
No changing arbitrary content in the string. Concatenation is a process of creating new strings.
But you're allowing assignment. That's not acting "as if it's const, with no way to modify the string"
Unless you frame assignment in terms of a "move".
x = "This is the original"; x = "Not anymore";
What's happening here is that you're really making x refer to a different string. In essence, x is what you might call a proxy. You can change what the proxy refers to, but what it refers to you cannot change -- if that makes any sense. If you're reading or dealing with x, basically you're dealing with the proxy.
Sorry, no, that's not value semantics. Value semantics are a subset of Stepanov's "Regular Type" concept. See EOP. Let me be clear: when you assign into x, you are modifying its value. If that can happen when x is const, x doesn't have proper value semantics. Implementation details like underlying buffers and refcounting are irrelevant. -- Dave Abrahams BoostPro Computing http://www.boostpro.com