Unipath

An object-oriented approach to file/directory operations

Unipath is an object-oriented front end to the file/directory functions scattered throughout several Python library modules. It's based on Jason Orendorff's path.py but focuses more on user convenience rather than on strict adherence to the underlying functions' syntax. Unipath is stable, well-tested, and has been used in production since 2008. It runs on Python 2.6+ and 3.2+.

Version 1.1 is a bugfix release. It fixes a Unicode incompatibility on Python 3 under Windows (or operating systems with native unicode filenames). The license is changed to MIT. It's as permissive as the former Python license but is smaller and simpler to read.

Python 3.4 introduced another object-oriented path library, pathlib. It's available on PyPI as pathlib2 for older versions of Python. (pathlib on PyPI is a frozen earlier version.) Unipath is now in maintenance mode. The author is exploring a subclass of pathlib(2) adding some of Unipath's features.

Introduction

The Path class encapsulates the file/directory operations in Python's os, os.path, and shutil modules. (Non-filesystem operations are in the AbstractPath superclass, but users can ignore this.)

The API has been streamlined to focus on what the application developer wants to do rather than on the lowest-level operations; e.g., .mkdir() succeeds silently if the directory already exists, and .rmtree() doesn't barf if the target is a file or doesn't exist. This allows the developer to write simple calls that "just work" rather than entire if-stanzas to handle low-level details s/he doesn't care about. This makes applications more self-documenting and less cluttered.

Convenience methods:

• .read_file and .write_file encapsulate the open/read/close pattern.
• .needs_update(others) tells whether the path needs updating; i.e., if it doesn't exist or is older than any of the other paths.
• .ancestor(N) returns the Nth parent directory, useful for joining paths.
• .child(\*components) is a "safe" version of join.
• .split_root() handles slash/drive/UNC absolute paths in a uniform way.

Sample usage for pathname manipulation:

>>> from unipath import Path
>>> p = Path("/usr/lib/python2.5/gopherlib.py")
>>> p.parent
Path("/usr/lib/python2.5")
>>> p.name
Path("gopherlib.py")
>>> p.ext
'.py'
>>> p.stem
Path('gopherlib')
>>> q = Path(p.parent, p.stem + p.ext)
>>> q
Path('/usr/lib/python2.5/gopherlib.py')
>>> q == p
True

Sample usage for filesystem access:

>>> import tempfile
>>> from unipath import Path
>>> d = Path(tempfile.mkdtemp())
>>> d.isdir()
True
>>> p = Path(d, "sample.txt")
>>> p.exists()
False
>>> p.write_file("The king is a fink!")
>>> p.exists()
True
>>> print(p.read_file())
The king is a fink!
>>> d.rmtree()
>>> p.exists()
False

Path objects subclass str (Python 2 unicode), so they can be passed directly to fuctions expecting a string path. They are also immutable and can be used as dictionary keys.

The name "Unipath" is short for "universal path". It was originally intended to unify the competing path APIs as of PEP 334. When the PEP was rejected, Unipath added some convenience APIs. The code is implemented in layers, with filesystem-dependent code in the Path class and filesystem-independent code in its AbstractPath superclass.

Installation and testing

Run "pip install Unipath". Or to install the development version, check out the source from the Git repository above and run "python setup.py develop".

To test the library, install 'pytest' and run "pytest test.py". It also comes with a Tox INI file.

Path and AbstractPath objects

Constructor

Path (and AbstractPath) objects can be created from a string path, or from several string arguments which are joined together a la os.path.join. Each argument can be a string, an (Abstract)Path instance, an int or long, or a list/tuple of strings to be joined:

p = Path("foo/bar.py")       # A relative path
p = Path("foo", "bar.py")    # Same as previous
p = Path(["foo", "bar.py"])  # Same as previous
p = Path("/foo", "bar", "baz.py")       # An absolute path: /foo/bar/baz.py
p = Path("/foo", Path("bar/baz.py"))    # Same as previous
p = Path("/foo", ["", "bar", "baz.py"]) # Embedded Path.components() result
p = Path("record", 123)      # Same as Path("record/123")

p = Path("")     # An empty path
p = Path()       # Same as Path(os.curdir)

To get the actual current directory, use Path.cwd(). (This doesn't work with AbstractPath, of course.

Adding two paths results in a concatenated path. The other string methods return strings, so you'll have to wrap them in Path to make them paths again. A future version will probably override these methods to return paths. Multiplying a path returns a string, as if you'd ever want to do that.

Normalization

The new path is normalized to clean up redundant ".." and "." in the middle, double slashes, wrong-direction slashes, etc. On case-insensitive filesystems it also converts uppercase to lowercase. This is all done via os.path.normpath(). Here are some examples of normalizations:

a//b  => a/b
a/../b => b
a/./b => a/b

a/b => a\\b            # On NT.
a\\b.JPG => a\\b.jpg   # On NT.

If the actual filesystem path contains symbolic links, normalizing ".." goes to the parent of the symbolic link rather than to the parent of the linked-to file. For this reason, and because there may be other cases where normalizing produces the wrong path, you can disable automatic normalization by setting the .auto_norm class attribute to false. I'm not sure whether Unipath should normalize by default, so if you care one way or the other you should explicitly set it at the beginning of your application. You can override the auto_norm setting by passing "norm=True" or "norm=False" as a keyword argument to the constructor. You can also call .norm() anytime to manually normalize the path.

Properties

Path objects have the following properties:

.parent

The path without the final component.

.name

The final component only.

.ext

The last part of the final component beginning with a dot (e.g., ".gz"), or "" if there is no dot. This is also known as the extension.

.stem

The final component without the extension.

Examples are given in the first sample usage above.

Methods

Path objects have the following methods:

.ancestor(N)

Same as specifying .parent N times.

.child(*components)

Join paths in a safe manner. The child components may not contain a path separator or be curdir or pardir ("." or ".." on Posix). This is to prevent untrusted arguments from creating a path above the original path's directory.

.components()

Return a list of directory components as strings. The first component will be the root ("/" on Posix, a Windows drive root, or a UNC share) if the path is absolute, or "" if it's relative. Calling Path(components), Path(*components), or os.path.join(*components) will recreate the original path.

.expand()

Same as p.expand_user().expand_vars().norm(). Usually this is all you need to fix up a path read from a config file.

.expand_user()

Interpolate "~" and "~user" if the platform allows, and return a new path.

.expand_vars()

Interpolate environment variables like "$BACKUPS" if the platform allows, and return a new path.

.isabsolute()

Is the path absolute?

.norm()

See Normalization above. Same as os.path.normpath.

.norm_case()

On case-insensitive platforms (Windows) convert the path to lower case. On case-sensitive platforms (Unix) leave the path as is. This also turns forward slashes to backslashes on Windows.

.split_root()

Split this path at the root and return a tuple of two paths: the root and the rest of the path. The root is the same as the first subscript of the .components() result. Calling Path(root, rest) or os.path.join(root, rest) will produce the original path.

Examples:

Path("foo/bar.py").components() =>
    [Path(""), Path("foo"), Path("bar.py")]
Path("foo/bar.py").split_root() =>
    (Path(""), Path("foo/bar.py"))

Path("/foo/bar.py").components() =>
    [Path("/"), Path("foo"), Path("bar.py")]
Path("/foo/bar.py").split_root() =>
    (Path("/"), Path("foo/bar.py"))

Path("C:\\foo\\bar.py").components() =>
    ["Path("C:\\"), Path("foo"), Path("bar.py")]
Path("C:\\foo\\bar.py").split_root() =>
    ("Path("C:\\"), Path("foo\\bar.py"))

Path("\\\\UNC_SHARE\\foo\\bar.py").components() =>
    [Path("\\\\UNC_SHARE"), Path("foo"), Path("bar.py")]
Path("\\\\UNC_SHARE\\foo\\bar.py").split_root() =>
    (Path("\\\\UNC_SHARE"), Path("foo\\bar.py"))

Path("~/bin").expand_user() => Path("/home/guido/bin")
Path("~timbot/bin").expand_user() => Path("/home/timbot/bin")
Path("$HOME/bin").expand_vars() => Path("/home/guido/bin")
Path("~//$BACKUPS").expand() => Path("/home/guido/Backups")

Path("dir").child("subdir", "file") => Path("dir/subdir/file")

Path("/foo").isabsolute() => True
Path("foo").isabsolute() => False

Note: a Windows drive-relative path like "C:foo" is considered absolute by .components(), .isabsolute(), and .split_root(), even though Python's ntpath.isabs() would return false.

Path objects only

Note on arguments

All arguments that take paths can also take strings.

Current directory

Path.cwd()

Return the actual current directory; e.g., Path("/tmp/my_temp_dir"). This is a class method.

.chdir()

Make self the current directory.

Calculating paths

.resolve()

Return the equivalent path without any symbolic links. This normalizes the path as a side effect.

.absolute()

Return the absolute equivalent of self. If the path is relative, this prefixes the current directory; i.e., FSPath(FSPath.cwd(), p).

.relative()

Return an equivalent path relative to the current directory if possible. This may return a path prefixed with many "../..". If the path is on a different drive, this returns the original path unchanged.

.rel_path_to(other)

Return a path from self to other. In other words, return a path for 'other' relative to self.

Listing directories

.listdir(pattern=None, filter=ALL, names_only=False)

Return the filenames in this directory.

'pattern' may be a glob expression like "*.py".

'filter' may be a function that takes a FSPath and returns true if it should be included in the results. The following standard filters are defined in the unipath module:

• DIRS: directories only
• FILES: files only
• LINKS: symbolic links only
• FILES_NO_LINKS: files that aren't symbolic links
• DIRS_NO_LINKS: directories that aren't symbolic links
• DEAD_LINKS: symbolic links that point to nonexistent files

This method normally returns FSPaths prefixed with 'self'. If 'names_only' is true, it returns the raw filenames as strings without a directory prefix (same as os.listdir).

If both 'pattern' and 'filter' are specified, only paths that pass both are included. 'filter' must not be specified if 'names_only' is true.

Paths are returned in sorted order.

.walk(pattern=None, filter=None, top_down=True)

Yield FSPath objects for all files and directories under self, recursing subdirectories. Paths are yielded in sorted order.

'pattern' and 'filter' are the same as for .listdir().

If 'top_down' is true (default), yield directories before yielding the items in them. If false, yield the items first.

File attributes and permissions

.atime()

Return the path's last access time.

.ctime()

Return the path's ctime. On Unix this returns the time the path's permissions and ownership were last modified. On Windows it's the path creation time.

.exists()

Does the path exist? For symbolic links, True if the linked-to file exists. On some platforms this returns False if Python does not have permission to stat the file, even if it exists.

.isdir()

Is the path a directory? Follows symbolic links.

.isfile()

Is the path a file? Follows symbolic links.

.islink()

Is the path a symbolic link?

.ismount()

Is the path a mount point? Returns true if self's parent is on a different device than self, or if self and its parent are the same directory.

.lexists()

Same as .exists() but don't follow a final symbolic link.

.lstat()

Same as .stat() but do not follow a final symbolic link.

.size()

Return the file size in bytes.

.stat()

Return a stat object to test file size, type, permissions, etc. See os.stat() for details.

.statvfs()

Return a StatVFS object. This method exists only if the platform supports it. See os.statvfs() for details.

Modifying paths

Creating/renaming/removing

.chmod(mode)

Change the path's permissions. 'mode' is octal; e.g., 0777.

.chown(uid, gid)

Change the path's ownership to the numeric uid and gid specified. Pass -1 if you don't want one of the IDs changed.

.mkdir(parents=False)

Create the directory, or succeed silently if it already exists. If 'parents' is true, create any necessary ancestor directories.

.remove()

Delete the file. Raises OSError if it's a directory.

.rename(dst, parents=False)

Rename self to 'dst' atomically. See os.rename() for additional details. If 'parents' is True, create any intermediate destination directories necessary, and delete as many empty leaf source directories as possible.

.rmdir(parents=False)

Remove the directory, or succeed silently if it's already gone. If 'parents' is true, also remove as many empty ancestor directories as possible.

.set_times(mtime=None, atime=None)

Set the path's modification and access times. If 'mtime' is None, use the current time. If 'atime' is None or not specified, use the same time as 'mtime'. To set the times based on another file, see .copy_stat().

Symbolic and hard links

.hardlink(src)

Create a hard link at 'src' pointing to self.

.write_link(target)

Create a symbolic link at self pointing to 'target'. The link will contain the exact string value of 'target' without checking whether that path exists or is a even a valid path for the filesystem.

.make_relative_link_to(dst)

Make a relative symbolic link from self to dst. Same as self.write_link(self.rel_path_to(dst)). (New in Unipath 0.2.0.)

.read_link()

Return the path that this symbolic link points to.

High-level operations

.copy(dst, times=False, perms=False)

Copy the file to a destination. 'times' and 'perms' are same as for .copy_stat().

.copy_stat(dst, times=True, perms=True)

Copy the access/modification times and/or the permission bits from this path to another path.

.move(dst)

Recursively move a file or directory to another location. This uses .rename() if possible.

.needs_update(other_paths)

Return True if self is missing or is older than any other path. 'other_paths' can be a (FS)Path, a string path, or a list/tuple of these. Recurses through subdirectories but compares only files.

.read_file(mode="r")

Return the file's content as a str string. This encapsulates the open/read/close. 'mode' is the same as in Python's open() function.

.rmtree(parents=False)

Recursively remove this path, no matter whether it's a file or a directory. Succeed silently if the path doesn't exist. If 'parents' is true, also try to remove as many empty ancestor directories as possible.

.write_file(content, mode="w")

Replace the file's content, creating the file if necessary. 'mode' is the same as in Python's open() function. 'content' is a str string. You'll have to encode Unicode strings before calling this.

Tools

The following functions are in the unipath.tools module.

dict2dir

dict2dir(dir, dic, mode="w") => None

Create a directory that matches the dict spec. String values are turned into files named after the key. Dict values are turned into subdirectories. 'mode' specifies the mode for files. 'dir' can be an [FS]Path or a string path.

dump_path(path, prefix="", tab=" ", file=None) => None

Display an ASCII tree of the path. Files are displayed as "filename (size)". Directories have ":" at the end of the line and indentation below, like Python syntax blocks. Symbolic links are shown as "link -> target". 'prefix' is a string prefixed to every line, normally to controll indentation. 'tab' is the indentation added for each directory level. 'file' specifies an output file object, or None for sys.stdout.

A future version of Unipath will have a command-line program to dump a path.

Acknowledgments

Jason Orendorff wrote the original path.py. Reinhold Birkenfeld and Björn Lindkvist modified it for Python PEP 335. Mike Orr changed the API and released it as Unipath. Ricardo Duarte ported it to Python 3, changed the tests to py.test, and added Tox support.

Comparision with os/os.path/shutil and path.py

p = any path, f =  file, d = directory, l = link
fsp, fsf, fsd, fsl = filesystem path (i.e., ``Path`` only)
- = not implemented

Functions are listed in the same order as the Python Library Reference, version 2.5. (Does not reflect later changes to Python or path.py.)

os/os.path/shutil      path.py        Unipath           Notes
=================      ============== ==========        =======
os.path.abspath(p)     p.abspath()    p.absolute()     Return absolute path.
os.path.basename(p)    p.name         p.name
os.path.commonprefix(p)  -            -                Common prefix. [1]_
os.path.dirname(p)     p.parent       p.parent         All except the last component.
os.path.exists(p)      p.exists()     fsp.exists()     Does the path exist?
os.path.lexists(p)     p.lexists()    fsp.lexists()    Does the symbolic link exist?
os.path.expanduser(p)  p.expanduser() p.expand_user()  Expand "~" and "~user" prefix.
os.path.expandvars(p)  p.expandvars() p.expand_vars()  Expand "$VAR" environment variables.
os.path.getatime(p)    p.atime        fsp.atime()      Last access time.
os.path.getmtime(p)    p.mtime        fsp.mtime()      Last modify time.
os.path.getctime(p)    p.ctime        fsp.ctime()      Platform-specific "ctime".
os.path.getsize(p)     p.size         fsp.size()       File size.
os.path.isabs(p)       p.isabs()      p.isabsolute     Is path absolute?
os.path.isfile(p)      p.isfile()     fsp.isfile()     Is a file?
os.path.isdir(p)       p.isdir()      fsp.isdir()      Is a directory?
os.path.islink(p)      p.islink()     fsp.islink()     Is a symbolic link?
os.path.ismount(p)     p.ismount()    fsp.ismount()    Is a mount point?
os.path.join(p, "Q/R") p.joinpath("Q/R")  [FS]Path(p, "Q/R")  Join paths.
                                          -or-
                                          p.child("Q", "R")
os.path.normcase(p)    p.normcase()    p.norm_case()   Normalize case.
os.path.normpath(p)    p.normpath()    p.norm()        Normalize path.
os.path.realpath(p)    p.realpath()    fsp.real_path() Real path without symbolic links.
os.path.samefile(p, q) p.samefile(q)   fsp.same_file(q)  True if both paths point to the same filesystem item.
os.path.sameopenfile(d1, d2)  -          -               [Not a path operation.]
os.path.samestat(st1, st2)    -          -               [Not a path operation.]
os.path.split(p)       p.splitpath()   (p.parent, p.name) Split path at basename.
os.path.splitdrive(p)  p.splitdrive()   -                 [2]_
os.path.splitext(p)    p.splitext()     -                 [2]_
os.path.splitunc(p)    p.splitunc()     -                 [2]_
os.path.walk(p, func, args)  -          -                 [3]_

os.access(p, const)    p.access(const)  -                 [4]_
os.chdir(d)            -                fsd.chdir()       Change current directory.
os.fchdir(fd)          -                -                 [Not a path operation.]
os.getcwd()           path.getcwd()     FSPath.cwd()      Get current directory.
os.chroot(d)          d.chroot()        -                 [5]_
os.chmod(p, 0644)     p.chmod(0644)     fsp.chmod(0644)     Change mode (permission bits).
os.chown(p, uid, gid) p.chown(uid, gid) fsp.chown(uid, gid) Change ownership.
os.lchown(p, uid, gid) -                -                 [6]_
os.link(src, dst)     p.link(dst)       fsp.hardlink(dst)   Make hard link.
os.listdir(d)         -                 fsd.listdir(names_only=True)  List directory; return base filenames.
os.lstat(p)           p.lstat()         fsp.lstat()         Like stat but don't follow symbolic link.
os.mkfifo(p, 0666)    -                 -                 [Not enough of a path operation.]
os.mknod(p, ...)      -                 -                 [Not enough of a path operation.]
os.major(device)      -                 -                 [Not a path operation.]
os.minor(device)      -                 -                 [Not a path operation.]
os.makedev(...)       -                 -                 [Not a path operation.]
os.mkdir(d, 0777)     d.mkdir(0777)     fsd.mkdir(mode=0777)     Create directory.
os.makedirs(d, 0777)  d.makedirs(0777)  fsd.mkdir(True, 0777)    Create a directory and necessary parent directories.
os.pathconf(p, name)  p.pathconf(name)  -                  Return Posix path attribute.  (What the hell is this?)
os.readlink(l)        l.readlink()      fsl.read_link()      Return the path a symbolic link points to.
os.remove(f)          f.remove()        fsf.remove()       Delete file.
os.removedirs(d)      d.removedirs()    fsd.rmdir(True)    Remove empty directory and all its empty ancestors.
os.rename(src, dst)   p.rename(dst)     fsp.rename(dst)      Rename a file or directory atomically (must be on same device).
os.renames(src, dst)  p.renames(dst)    fsp.rename(dst, True) Combines os.rename, os.makedirs, and os.removedirs.
os.rmdir(d)           d.rmdir()         fsd.rmdir()        Delete empty directory.
os.stat(p)            p.stat()          fsp.stat()         Return a "stat" object.
os.statvfs(p)         p.statvfs()       fsp.statvfs()      Return a "statvfs" object.
os.symlink(src, dst)  p.symlink(dst)    fsp.write_link(link_text)   Create a symbolic link.
                                        ("write_link" argument order is opposite from Python's!)
os.tempnam(...)       -                 -                  [7]_
os.unlink(f)          f.unlink()        -                  Same as .remove().
os.utime(p, times)    p.utime(times)    fsp.set_times(mtime, atime)  Set access/modification times.
os.walk(...)          -                 -                  [3]_

shutil.copyfile(src, dst)  f.copyfile(dst) fsf.copy(dst, ...)  Copy file.  Unipath method is more than copyfile but less than copy2.
shutil.copyfileobj(...)   -             -                  [Not a path operation.]
shutil.copymode(src, dst) p.copymode(dst)  fsp.copy_stat(dst, ...)  Copy permission bits only.
shutil.copystat(src, dst) p.copystat(dst)  fsp.copy_stat(dst, ...)  Copy stat bits.
shutil.copy(src, dst)  f.copy(dst)      -                  High-level copy a la Unix "cp".
shutil.copy2(src, dst) f.copy2(dst)     -                  High-level copy a la Unix "cp -p".
shutil.copytree(...)  d.copytree(...)   fsp.copy_tree(...)   Copy directory tree.  (Not implemented in Unipath 0.1.0.)
shutil.rmtree(...)    d.rmtree(...)     fsp.rmtree(...)    Recursively delete directory tree.  (Unipath has enhancements.)
shutil.move(src, dst) p.move(dst)       fsp.move(dst)      Recursively move a file or directory, using os.rename() if possible.

A + B                 A + B             A+B                Concatenate paths.
os.path.join(A, B)    A / B             [FS]Path(A, B)     Join paths.
                                        -or-
                                        p.child(B)
-                     p.expand()        p.expand()         Combines expanduser, expandvars, normpath.
os.path.dirname(p)    p.parent          p.parent           Path without final component.
os.path.basename(p)   p.name            p.name             Final component only.
[8]_                  p.namebase        p.stem             Final component without extension.
[9]_                  p.ext             p.ext              Extension only.
os.path.splitdrive(p)[0] p.drive        -                  [2]_
-                     p.stripext()      -                  Strip final extension.
-                     p.uncshare        -                  [2]_
-                     p.splitall()      p.components()     List of path components.  (Unipath has special first element.)
-                     p.relpath()       fsp.relative()       Relative path to current directory.
-                     p.relpathto(dst)  fsp.rel_path_to(dst) Relative path to 'dst'.
-                     d.listdir()       fsd.listdir()        List directory, return paths.
-                     d.files()         fsd.listdir(filter=FILES)  List files in directory, return paths.
-                     d.dirs()          fsd.listdir(filter=DIRS)   List subdirectories, return paths.
-                     d.walk(...)       fsd.walk(...)        Recursively yield files and directories.
-                     d.walkfiles(...)  fsd.walk(filter=FILES)  Recursively yield files.
-                     d.walkdirs(...)   fsd.walk(filter=DIRS)  Recursively yield directories.
-                     p.fnmatch(pattern)  -                 True if self.name matches glob pattern.
-                     p.glob(pattern)   -                   Advanced globbing.
-                     f.open(mode)      -                   Return open file object.
-                     f.bytes()         fsf.read_file("rb")   Return file contents in binary mode.
-                     f.write_bytes()   fsf.write_file(content, "wb")  Replace file contents in binary mode.
-                     f.text(...)       fsf.read_file()       Return file content.  (Encoding args not implemented yet.)
-                     f.write_text(...) fsf.write_file(content)  Replace file content.  (Not all Orendorff args supported.)
-                     f.lines(...)      -                   Return list of lines in file.
-                     f.write_lines(...)  -                 Write list of lines to file.
-                     f.read_md5()      -                   Calculate MD5 hash of file.
-                     p.owner           -                   Advanded "get owner" operation.
-                     p.readlinkabs()   -                   Return the path this symlink points to, converting to absolute path.
-                     p.startfile()     -                   What the hell is this?

-                     -                 p.split_root()      Unified "split root" method.
-                     -                 p.ancestor(N)       Same as specifying .parent N times.
-                     -                 p.child(...)        "Safe" way to join paths.
-                     -                 fsp.needs_update(...) True if self is missing or older than any of the other paths.