On Mar 26, 2007, at 2:47 PM, Peter Dimov wrote:
But my question is more along the lines of: why does the const/non- const label matter when we decide on the precondition and thread safety of t.cancel? If t.cancel is always valid on a valid t, this makes sharing possible and safe, regardless of whether thread::cancel is declared const.
I guess my answer would go back to this snippet: void foo(const thread& t); void bar() { std::thread t(f); ... foo(t); ... } Because of the const qualifier on the thread& which foo takes as a parameter, and knowing that the const interface of thread is a subset of the non-const interface, we can make useful assumptions about t after the call to foo() (such as t hasn't been canceled). This might be particularly helpful if foo is a virtual function. -Howard