[Nat] I guess I have a couple of comments.

One is that a character substitution pass is still cheaper than the directory parsing and other goodies that boost::filesystem gets you.

Speed is not a concern.

The other is to ask why your *nix requirements include backslashes as directory separators? Backslashes have other significance everywhere but Windows, which is presumably why boost::filesystem::path wasn't written to treat '\' and '/' interchangeably on all platforms. Backslashes (and forward slashes) work on Windows, forward slashes work elsewhere, all per convention.

I work on a large application that runs on Windows and Linux and interacts with various 3rd party applications on either platform, all of them designed with only the dedicated platform in mind and thus using native syntax. Ongoing development now warrants that we interact with the Windows apps from Linux and vice versa. In the midst of all this it becomes inevitable to run into the occasional Windows file path on Linux (or Linux path on Windows)(usually through file IO). I use portable paths wherever I can but I don't have control over all the input.

You seem disappointed that boost::filesystem::path doesn't treat backslashes as directory separators on non-Windows systems.

Not quite, I am disappointed that the library eliminates the code to treat backslashes as directory separators at compile-time on non-Windows systems and doesn't provide me with an option to explicitly enable this code for the few file paths that I know will have a Windows syntax. Note that because Windows supports either directory separator it is possible to parse a Linux relative file path on Windows (with minimal limitations). This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender. Thank you.