Re: [boost] FW: [filesystem] : basic_path : Feature request

Subject: Re: [boost] FW: [filesystem] : basic_path : Feature request
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2009-02-07 15:30:36

On Sat, Feb 7, 2009 at 2:55 AM, Rob <robrimmer_at_[hidden]> wrote:
>> These seem like reasonable requests, although I'd have to check the
>> std::back_inserter to be 100% sure.
>>
> I have checked this using a wrapper around path as follows
>
> template<class String, class Traits>
> struct rob_basicpath
>  :  boost::filesystem::basic_path<String, Traits>
> {
>  typedef string_type& reference;
>  typedef const string_type& const_reference;
>
>  inline void push_back(const_reference path)
>  {
>    *this /= path;
>  }
> };
>
> This allowed me to use the following code as expected (which strips .
> characters from the path)
>
> const boost::filesystem::path path("dir1/./dir2/./dir3");
> rob_path rpath;
> std::remove_copy(path.begin(), path.end(), std::back_inserter(rpath), ".");

Arguably the problem here isn't with basic_path, but with
std::back_inserter, which insists on push_back being a member
function. You could write your own path_inserter or something.

>> Note however that path has some but not all of the characteristics of
>> a standard container. I'd want to see persuasive use cases for adding
>> functionality - just making path more like a std container without
>> good reason is likely to lead to interface bloat without offsetting
>> benefits.

I have to second this, all path member functions that take a string
apply a transformation to establish the path's invariant, it wouldn't
make sense to make it feel more like a container of chars.

> 2. A variety of tasks I envisage on a path can be neatly and succinctly
> implemented using std algorithms. <snipped>

The solution is to convert it to string, do what you want with it,
then convert it back to a path.

Alternatively, you can store paths as strings, and only convert them
to filesystem::path when you need to do some kind of path operation on
them. Btw, this seems very reasonable approach, given that many paths
originate as strings (as user input or read from files, or passed by
3rd party code) and end up as strings (when calling fopen, etc.)

Emil Dotchevski
Reverge Studios, Inc.
http://www.revergestudios.com/reblog/index.php?n=ReCode