"Andy Little" <andy@servocomm.freeserve.co.uk> writes:
"David Abrahams" <dave@boost-consulting.com> wrote in message news:uk6xhf6kh.fsf@boost-consulting.com...
"Andy Little" <andy@servocomm.freeserve.co.uk> writes:
"David Abrahams" <dave@boost-consulting.com> wrote
"Andy Little" <andy@servocomm.freeserve.co.uk> writes:
"David Abrahams" <dave@boost-consulting.com> wrote
You say you're talking about "operations not types", but I think
hmmm.. Actual quote is " I am talking about operations rather than types after all."
Did my (mis)quoting differ in substance, or can we forget it?
you're just mystifying something that's simple. Whether or not multiplication is commutative depends entirely on the types of its operands.
Whether or not a binary operation is commutative depends on the operator and the types and values of its operands.
int x=10,y=x; assert(y/x == x/y);assert(y-x == x-y);
Sure.
I found output of (say) operator + as "+" useful in following the execution of expression templates. "super-functional" is an off-the-cuff replacement for <functional>. Dont take it too seriously, but std::plus etc are past their best. If I wish to know whether an operation on two types is commutative, I might like to be able to quiz the operation about it. decltype wont do that for me.
And neither should that trait be glommed into the one used for determining result types.
Keep talking... youre winning me over... Though I shall mourn glomming.. for it is a less practised art...
Whatever that means. I'm not sure it's an art, and I'm not convinced it's less-practiced than separation-of-concerns, which is what I'm advocating. I see glomming ("Blob-ing", really) all over.
3) typeof, decltype etc is not standard C++ as it stands. Its a non-starter.
Not neccessarily. We can build a pretty nice typeof replacement that requires just a little help from users.
Any documentation of this you can point me to ....? I hope "a little help from users " means what it says.
It means registering user-defined types and templates that may participate in the result type. Arkadiy's typeof from the Boost Files area at yahoogroups: http://tinyurl.com/32mlf No docs, lots of examples. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com