On 7/11/06 6:17 AM, "Peter Dimov" <pdimov@mmltd.net> wrote:
Daryle Walker wrote:
[1] If you make a fake order for "std::complex<>", would you compare real components then imaginary components, or would you use magnitude then angle?
Real, then imaginary. Compare with:
It wasn't a challenge. It was just an example. I got the idea of it from _The C++ Standard Library_ book by Nicolai M. Josuttis, who asked help from David Vandevoorde on explaining why std::complex didn't have ordering. I looked at the "Comparison Operations" part of section 12.1.2. (In this section, Mr. Josuttis mentions the fake operator "<" trick, but warns against polluting the standard namespace when defining an operator for std::complex. He also mentions using a user-defined criterion.)
"If you make a FAKE order for std::string, would you compare left to right or right to left?"
You don't need to define a "fake" order since std::string already comes with ordering operators, and it comes with all of them. (Defining operator "<" and deciding to skip the ">", "<=", and ">=" operators is a code smell.) The ordering is lexicographic, which is left-to-right, assuming that's the direction you write your letters. If std::string didn't have ordering operators, I could provide comparison types for _both_ ways and let the user decide. If you decided to pick a direction for operator "<" by fiat, users that needed the other direction would have to make up a custom class anyway! -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com