ThePath - Convenient lib to deal with paths and files. (Alpha version)

[Dmytro Katyukha]

Hi,

I would like to anounce the new 
[ThePath](https://code.dlang.org/packages/thepath) published to 
https://code.dlang.org/.

The basic functionality of 
[ThePath](https://code.dlang.org/packages/thepath) library seems 
to be completed, and before stabilizing it, i would like to ask 
community to review this lib and suggest what could be added / 
changed to make it usable for your usecases. Also, currently, 
this lib is tested only on linux, thus, may be some of you would 
be interested in making it cross-platform (help with testing and 
adding unittests for other platforms (Windows, MacOs, etc)). It 
should work on other platforms, but possibly with restricted 
functionality.

Basically, this lib provides single struct `Path`, that have to 
be used to deal with file system paths and files in 
object-oriented way, making code more readable.

Also, this lib contains function 
[createTempDirectory](https://github.com/katyukha/thepath/blob/master/source/thepath/utils.d), that, i think, would be nice to have it in Phobos.

So, the questions are:
- Do it have sense to convert `Path` to a class? Or keep it as 
struct?
- Do it have sense to convert `Path` to template struct to make 
it possible to work with other types of strings (except `string` 
type)?
- What are the requirements to place 
[createTempDirectory](https://github.com/katyukha/thepath/blob/master/source/thepath/utils.d#L11) function in Phobos?
- What else could be changed to make it better?

Short list of features:
- automatic expansion of `~` when needed (before passing path to 
std.file or std.stdio funcs)
- single method to copy path (file or directory) to dest path
- single method to remove path (file or directory)
- simple method to `walk` through the path
     - `foreach(p; Path.current.walk) writeln(p.toString);`
     - `foreach(p; Path("/tmp").walk) writeln(p.toString);`
- simple construction of paths from parts:
     - `Path("a", "b", "c")`
     - `Path("a").join("b", "c")`
- simple deconstruction of paths
     - `Path("a/b/c/d").segments == ["a", "b", "c", "d"]`
     - `Path("a", "b", "c", "d").segments == ["a", "b", "c", "d"]`
- overriden comparison operators for paths.
     - `Path("a", "b") == Path("a", "b")`
     - `Path("a", "b") != Path("a", "c")`
     - `Path("a", "b") < Path("a", "c")`
- `hasAttributes` / `getAttributes` / `setAttributes` methods to 
work with file attrs
- file operations as methods:
     - `Path("my-path").writeFile("Hello world")`
     - `Path("my-path").readFile()`
- support search by glob-pattern
     - `foreach(path; Path.current.glob("*.py")) 
writeln(p.toString);`


Short example is described below. More examples available in 
unittests and documentation.


```d
import thepath;


Path app_dir = Path("~/.local/my-app");
Path catalog_dir = app_dir.join("catalog");


void init() {
     // Note, that automatic '~' expansion will be done before 
checking the
     // existense of directory
     if (!app_dir.exists) {
         app_dir.mkdir(true);  // create recursive
     }
     if (!catalog_dir.exists) {
         catalog_dir.mkdir(true);
     }
}

void list_dir() {
     // Easily print content of the catalog directory
     foreach(Path p; catalog_dir.walkBreadth) {
         writeln(p.toAbsolute().toString());
     }
}

// Print all python files in current directory
void find_python_files() {
     foreach(path; Path.current.glob("*.py", SpanMode.breadth))
         // Print paths relative to current directory
         writeln(p.relativeTo(Path.current).toString);
}

Path findConfig() {
     // Search for "my-project.conf" in current directories and in
     // its parent directories
     auto config = Path.current.searchFileUp("my-project.conf");
     enforce(!config.isNull);
     return config.get;
}
```