Re: [boost] [filesystem] Version 3 of Boost.Filesystem added to trunk

Subject: Re: [boost] [filesystem] Version 3 of Boost.Filesystem added to trunk
From: Beman Dawes (bdawes_at_[hidden])
Date: 2010-06-04 06:47:36

On Thu, Jun 3, 2010 at 8:32 PM, Alexander Lamaison <awl03_at_[hidden]> wrote:
> On Thu, 3 Jun 2010 20:04:26 -0400, Beman Dawes wrote:
>
>> On Thu, Jun 3, 2010 at 6:48 PM, Alexander Lamaison <awl03_at_[hidden]> wrote:
>>> On Wed, 2 Jun 2010 11:07:34 -0400, Beman Dawes wrote:
>>>>
>>>> * Any other comments or suggestions?
>>>
>>> Some code I have wraps a SFTP library that returns paths as UTF-8 strings.
>>> These need to be converted to the local code page before displaying to the
>>> user.  My original plan was to typedef basic_path with a traits class of my
>>> own that I could imbue with a specific locale to do the conversion.
>>>
>>> With FSv3 the only way to do this seems to be path::imbue() which imbue
>>> *all* paths, globally.  Or am I missing something?
>>
>> Yep, there is another way. First convert the UTF-8 string to a UTF-16
>> string using software of your choice. Then construct a
>> boost::filesystem::path with the UTF-16 string as an argument.
>> Alternately, assign the UTF-16 string to a boost::filesystem::path.
>>
>> Say the resulting path is named p. Then p.string() will return a
>> std::string containing the path in native format, native codepage.
>>
>> Does that solve your problem?
>
> Possibly, I'll get back to you once I've actually tried implementing
> something.
>
> My next questions related to the Windows API A/W variants.  Another library
> I've written many generic functions that wrap these kinds of API calls by
> taking a basic_path and selecting the A or W variant depending on whether
> the caller passes a basic_string<char> or a basic_string<wchar_t>.  I
> imagine this is going to be hard to port to v3 if I still want the caller
> to be able to select the A or W variant.

That's essentially what the v2 implementation of operations functions
did. See libs/filesystem/src/operations.cpp.

Life got much simpler when I switched to just using the W variants.
I'm sorry I ever messed with the A variants.

> Is there any reason why I should even care about being able to call the A
> variants?  My original theory was that someone could write a program that
> always used basic_string<char> and could use that on Win9x but I've not
> actually tested that theory.

Are you willing to compromise your design and implementation so that
someone could use Win9x? I'm not:-)

Thanks for the comments and questions!

--Beman