Re: [boost] [Boost-commit] svn:boost r62919 - in trunk: boost/filesystem/v2 boost/filesystem/v3 libs/filesystem/v2/test libs/filesystem/v3/test

Subject: Re: [boost] [Boost-commit] svn:boost r62919 - in trunk: boost/filesystem/v2 boost/filesystem/v3 libs/filesystem/v2/test libs/filesystem/v3/test
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2010-06-14 08:15:41

On 06/14/2010 03:12 PM, Beman Dawes wrote:
> On Sun, Jun 13, 2010 at 1:47 PM, Scott McMurray<me22.ca+boost_at_[hidden]>  wrote:
>> On 13 June 2010 10:33,<bdawes_at_[hidden]>  wrote:
>>> Author: bemandawes
>>> Date: 2010-06-13 13:33:39 EDT (Sun, 13 Jun 2010)
>>> New Revision: 62919
>>> URL: http://svn.boost.org/trac/boost/changeset/62919
>>>
>>> [...]
>>>
>>> @@ -620,7 +620,7 @@
>>>          basic_path<  String, Traits>  &  ph )
>>>      {
>>>        String str;
>>> -      is>>  str;
>>> +      std::getline(is, str);  // See ticket 3863
>>>        ph = str;
>>>        return is;
>>>      }
>>>
>>
>> I'm not convinced this is the right approach here, since
>>
>>     cout<<  mypath<<  ' '<<  myint;
>>
>> doesn't roundtrip with
>>
>>     cin>>  mypath>>  myint;
>>
>> the way I expect operator<<  and operator>>  to work.
>
> I agree with you that there is a problem here.
>
>> Perhaps the portable pathname grammar could be extended to allow
>> backslash-escaping of spaces and backslashes?  That or remove the
>> stream operators entirely and force people to choose which way they
>> want to print the path and deal with the result as a fully-general
>> string.
>
> In thinking about your suggestion, and several similar approaches, I
> realized the problem isn't limited to filesystem::path. It pops up
> every time someone wants to stream string values.
>
> It should be pretty simple to write two function templates:
>
> For output:
>
>     template<String>
>     String delimit(const String&  s);
>
>     Returns: s wrapped in double-quote characters. Any double-quote
> characters in s are escaped.
>
> A similar function for input.
>
> I'll think this in more detail later today, but in the meantime
> perhaps someone else could flesh out this idea.

+1 for removing streaming operators for path. For diagnostic purposes it 
should be enough to have the path::string< CharT > method. For 
serialization purposes, I think, it's better to have a separate header 
that enables support for Boost.Serialization.

The escape/unescape functions (why "delimit"?) you mentioned could be 
useful, but only as helpers for other APIs (such as the OS API). I 
think, convenience.hpp is the right place for them.

Just my 2 cents.