Re: [Boost-users] [filestreams] Does native not work correctly inWindows?

From: Paul Giaccone (paulg_at_[hidden])
Date: 2006-02-13 04:55:52

Beman Dawes wrote:

>"Paul Giaccone" <paulg_at_[hidden]> wrote in message 
>news:43EC8417.8010000_at_cinesite.co.uk...
>  
>
>>The following line in my Windows program:
>>
>>   boost::filesystem::path my_path(my_filename, 
>>boost::filesystem::native);
>>
>>converts backslashes in my_filename to forward slashes, which means than
>>when I use boost::filesystem::exists on the result, the file is reported
>>as not existing even though it does.
>>
>>I notice the comments in boost::filesystem::m_path_append(), which is
>>called by the constructor of boost::filesystem::path, say that this is
>>what the function does, but this contradicts the documentation.
>>http://boost.org/libs/filesystem/doc/portability_guide.htm says, of 
>>native:
>>
>>   Side effect: Syntax for path constructor /src/ string is
>>implementation defined according to the path syntax rules for the
>>operating system.
>>
>>   Use: In path constructors, when the source is operator input or
>>other sources which are formatted according to operating system rules.
>>
>>I understand this to mean that boost::filesystem::native converts the
>>file into the format required by the OS.  I certainly would not expect
>>it to make the format wrong if it is already correct.
>>
>>Is there something I've overlooked here, or is this a bug, or is the
>>documentation wrong (or just misleading)?  I'm puzzled.
>>    
>>
>
>I assume you are using 1.33.1 or earlier. It certainly handles both back and 
>forward slashes correctly for the mostpart, although I wouldn't be surprised 
>if there were obsure bugs in corner cases such as \\? pathnames.
>
>Why don't you give the 1.34 version from the CVS HEAD a try. It uses a much 
>simplified (and hopefully improved) way of handling native formats. You no 
>longer have to do anything special such as using a special constructor 
>argument.
>
>Good luck,
>
>--Beman
>  
>

Thanks.  I was about to post an example of what I am doing, but, 
bizarrely, it's all working now.  The boost::filesystem::path is 
initialised from a std::string of the form 
<drive>:\<dir1>\<dir2>\....\<dirn>/<filename>.<extension> and the 
backslashes is converted to forward slashes.  The .string() function 
(and the .c_str() function on that) give strings containing forward 
slashes.  ::exists() says the file exists, and the file loads OK.  I'm 
using Windows Visual C++ 7.1.3088 and Boost 1.33.1.

I wonder what was wrong before.  The problem just seems to have gone 
away of its own accord.  I did not recompile the program or change the 
input.  Still, it's back to the correct behaviour, so I'm not complaining.

Thanks for your feedback in any case.

Paul