"pathlib" --- Object-oriented filesystem paths
**********************************************

3.4 版新加入.

**Source code:** Lib/pathlib.py

======================================================================

This module offers classes representing filesystem paths with
semantics appropriate for different operating systems.  Path classes
are divided between pure paths, which provide purely computational
operations without I/O, and concrete paths, which inherit from pure
paths but also provide I/O operations.

[圖片]

If you've never used this module before or just aren't sure which
class is right for your task, "Path" is most likely what you need. It
instantiates a concrete path for the platform the code is running on.

Pure paths are useful in some special cases; for example:

1. If you want to manipulate Windows paths on a Unix machine (or
   vice versa). You cannot instantiate a "WindowsPath" when running on
   Unix, but you can instantiate "PureWindowsPath".

2. You want to make sure that your code only manipulates paths
   without actually accessing the OS. In this case, instantiating one
   of the pure classes may be useful since those simply don't have any
   OS- accessing operations.

也參考: **PEP 428**: The pathlib module -- object-oriented
  filesystem paths.

也參考: For low-level path manipulation on strings, you can also use
  the "os.path" module.


Basic use
=========

Importing the main class:

   >>> from pathlib import Path

Listing subdirectories:

   >>> p = Path('.')
   >>> [x for x in p.iterdir() if x.is_dir()]
   [PosixPath('.hg'), PosixPath('docs'), PosixPath('dist'),
    PosixPath('__pycache__'), PosixPath('build')]

Listing Python source files in this directory tree:

   >>> list(p.glob('**/*.py'))
   [PosixPath('test_pathlib.py'), PosixPath('setup.py'),
    PosixPath('pathlib.py'), PosixPath('docs/conf.py'),
    PosixPath('build/lib/pathlib.py')]

Navigating inside a directory tree:

   >>> p = Path('/etc')
   >>> q = p / 'init.d' / 'reboot'
   >>> q
   PosixPath('/etc/init.d/reboot')
   >>> q.resolve()
   PosixPath('/etc/rc.d/init.d/halt')

Querying path properties:

   >>> q.exists()
   True
   >>> q.is_dir()
   False

Opening a file:

   >>> with q.open() as f: f.readline()
   ...
   '#!/bin/bash\n'


Pure paths
==========

Pure path objects provide path-handling operations which don't
actually access a filesystem.  There are three ways to access these
classes, which we also call *flavours*:

class pathlib.PurePath(*pathsegments)

   A generic class that represents the system's path flavour
   (instantiating it creates either a "PurePosixPath" or a
   "PureWindowsPath"):

      >>> PurePath('setup.py')      # Running on a Unix machine
      PurePosixPath('setup.py')

   Each element of *pathsegments* can be either a string representing
   a path segment, an object implementing the "os.PathLike" interface
   which returns a string, or another path object:

      >>> PurePath('foo', 'some/path', 'bar')
      PurePosixPath('foo/some/path/bar')
      >>> PurePath(Path('foo'), Path('bar'))
      PurePosixPath('foo/bar')

   When *pathsegments* is empty, the current directory is assumed:

      >>> PurePath()
      PurePosixPath('.')

   When several absolute paths are given, the last is taken as an
   anchor (mimicking "os.path.join()"'s behaviour):

      >>> PurePath('/etc', '/usr', 'lib64')
      PurePosixPath('/usr/lib64')
      >>> PureWindowsPath('c:/Windows', 'd:bar')
      PureWindowsPath('d:bar')

   However, in a Windows path, changing the local root doesn't discard
   the previous drive setting:

      >>> PureWindowsPath('c:/Windows', '/Program Files')
      PureWindowsPath('c:/Program Files')

   Spurious slashes and single dots are collapsed, but double dots
   ("'..'") are not, since this would change the meaning of a path in
   the face of symbolic links:

      >>> PurePath('foo//bar')
      PurePosixPath('foo/bar')
      >>> PurePath('foo/./bar')
      PurePosixPath('foo/bar')
      >>> PurePath('foo/../bar')
      PurePosixPath('foo/../bar')

   (a naïve approach would make "PurePosixPath('foo/../bar')"
   equivalent to "PurePosixPath('bar')", which is wrong if "foo" is a
   symbolic link to another directory)

   Pure path objects implement the "os.PathLike" interface, allowing
   them to be used anywhere the interface is accepted.

   3.6 版更變: Added support for the "os.PathLike" interface.

class pathlib.PurePosixPath(*pathsegments)

   A subclass of "PurePath", this path flavour represents non-Windows
   filesystem paths:

      >>> PurePosixPath('/etc')
      PurePosixPath('/etc')

   *pathsegments* is specified similarly to "PurePath".

class pathlib.PureWindowsPath(*pathsegments)

   A subclass of "PurePath", this path flavour represents Windows
   filesystem paths:

      >>> PureWindowsPath('c:/Program Files/')
      PureWindowsPath('c:/Program Files')

   *pathsegments* is specified similarly to "PurePath".

Regardless of the system you're running on, you can instantiate all of
these classes, since they don't provide any operation that does system
calls.


General properties
------------------

Paths are immutable and hashable.  Paths of a same flavour are
comparable and orderable.  These properties respect the flavour's
case-folding semantics:

   >>> PurePosixPath('foo') == PurePosixPath('FOO')
   False
   >>> PureWindowsPath('foo') == PureWindowsPath('FOO')
   True
   >>> PureWindowsPath('FOO') in { PureWindowsPath('foo') }
   True
   >>> PureWindowsPath('C:') < PureWindowsPath('d:')
   True

Paths of a different flavour compare unequal and cannot be ordered:

   >>> PureWindowsPath('foo') == PurePosixPath('foo')
   False
   >>> PureWindowsPath('foo') < PurePosixPath('foo')
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
   TypeError: '<' not supported between instances of 'PureWindowsPath' and 'PurePosixPath'


Operators
---------

The slash operator helps create child paths, similarly to
"os.path.join()":

   >>> p = PurePath('/etc')
   >>> p
   PurePosixPath('/etc')
   >>> p / 'init.d' / 'apache2'
   PurePosixPath('/etc/init.d/apache2')
   >>> q = PurePath('bin')
   >>> '/usr' / q
   PurePosixPath('/usr/bin')

A path object can be used anywhere an object implementing
"os.PathLike" is accepted:

   >>> import os
   >>> p = PurePath('/etc')
   >>> os.fspath(p)
   '/etc'

The string representation of a path is the raw filesystem path itself
(in native form, e.g. with backslashes under Windows), which you can
pass to any function taking a file path as a string:

   >>> p = PurePath('/etc')
   >>> str(p)
   '/etc'
   >>> p = PureWindowsPath('c:/Program Files')
   >>> str(p)
   'c:\\Program Files'

Similarly, calling "bytes" on a path gives the raw filesystem path as
a bytes object, as encoded by "os.fsencode()":

   >>> bytes(p)
   b'/etc'

備註: Calling "bytes" is only recommended under Unix.  Under
  Windows, the unicode form is the canonical representation of
  filesystem paths.


Accessing individual parts
--------------------------

To access the individual "parts" (components) of a path, use the
following property:

PurePath.parts

   A tuple giving access to the path's various components:

      >>> p = PurePath('/usr/bin/python3')
      >>> p.parts
      ('/', 'usr', 'bin', 'python3')

      >>> p = PureWindowsPath('c:/Program Files/PSF')
      >>> p.parts
      ('c:\\', 'Program Files', 'PSF')

   (note how the drive and local root are regrouped in a single part)


Methods and properties
----------------------

Pure paths provide the following methods and properties:

PurePath.drive

   A string representing the drive letter or name, if any:

      >>> PureWindowsPath('c:/Program Files/').drive
      'c:'
      >>> PureWindowsPath('/Program Files/').drive
      ''
      >>> PurePosixPath('/etc').drive
      ''

   UNC shares are also considered drives:

      >>> PureWindowsPath('//host/share/foo.txt').drive
      '\\\\host\\share'

PurePath.root

   A string representing the (local or global) root, if any:

      >>> PureWindowsPath('c:/Program Files/').root
      '\\'
      >>> PureWindowsPath('c:Program Files/').root
      ''
      >>> PurePosixPath('/etc').root
      '/'

   UNC shares always have a root:

      >>> PureWindowsPath('//host/share').root
      '\\'

PurePath.anchor

   The concatenation of the drive and root:

      >>> PureWindowsPath('c:/Program Files/').anchor
      'c:\\'
      >>> PureWindowsPath('c:Program Files/').anchor
      'c:'
      >>> PurePosixPath('/etc').anchor
      '/'
      >>> PureWindowsPath('//host/share').anchor
      '\\\\host\\share\\'

PurePath.parents

   An immutable sequence providing access to the logical ancestors of
   the path:

      >>> p = PureWindowsPath('c:/foo/bar/setup.py')
      >>> p.parents[0]
      PureWindowsPath('c:/foo/bar')
      >>> p.parents[1]
      PureWindowsPath('c:/foo')
      >>> p.parents[2]
      PureWindowsPath('c:/')

PurePath.parent

   The logical parent of the path:

      >>> p = PurePosixPath('/a/b/c/d')
      >>> p.parent
      PurePosixPath('/a/b/c')

   You cannot go past an anchor, or empty path:

      >>> p = PurePosixPath('/')
      >>> p.parent
      PurePosixPath('/')
      >>> p = PurePosixPath('.')
      >>> p.parent
      PurePosixPath('.')

   備註: This is a purely lexical operation, hence the following
     behaviour:

        >>> p = PurePosixPath('foo/..')
        >>> p.parent
        PurePosixPath('foo')

     If you want to walk an arbitrary filesystem path upwards, it is
     recommended to first call "Path.resolve()" so as to resolve
     symlinks and eliminate *".."* components.

PurePath.name

   A string representing the final path component, excluding the drive
   and root, if any:

      >>> PurePosixPath('my/library/setup.py').name
      'setup.py'

   UNC drive names are not considered:

      >>> PureWindowsPath('//some/share/setup.py').name
      'setup.py'
      >>> PureWindowsPath('//some/share').name
      ''

PurePath.suffix

   The file extension of the final component, if any:

      >>> PurePosixPath('my/library/setup.py').suffix
      '.py'
      >>> PurePosixPath('my/library.tar.gz').suffix
      '.gz'
      >>> PurePosixPath('my/library').suffix
      ''

PurePath.suffixes

   A list of the path's file extensions:

      >>> PurePosixPath('my/library.tar.gar').suffixes
      ['.tar', '.gar']
      >>> PurePosixPath('my/library.tar.gz').suffixes
      ['.tar', '.gz']
      >>> PurePosixPath('my/library').suffixes
      []

PurePath.stem

   The final path component, without its suffix:

      >>> PurePosixPath('my/library.tar.gz').stem
      'library.tar'
      >>> PurePosixPath('my/library.tar').stem
      'library'
      >>> PurePosixPath('my/library').stem
      'library'

PurePath.as_posix()

   Return a string representation of the path with forward slashes
   ("/"):

      >>> p = PureWindowsPath('c:\\windows')
      >>> str(p)
      'c:\\windows'
      >>> p.as_posix()
      'c:/windows'

PurePath.as_uri()

   Represent the path as a "file" URI.  "ValueError" is raised if the
   path isn't absolute.

   >>> p = PurePosixPath('/etc/passwd')
   >>> p.as_uri()
   'file:///etc/passwd'
   >>> p = PureWindowsPath('c:/Windows')
   >>> p.as_uri()
   'file:///c:/Windows'

PurePath.is_absolute()

   Return whether the path is absolute or not.  A path is considered
   absolute if it has both a root and (if the flavour allows) a drive:

      >>> PurePosixPath('/a/b').is_absolute()
      True
      >>> PurePosixPath('a/b').is_absolute()
      False

      >>> PureWindowsPath('c:/a/b').is_absolute()
      True
      >>> PureWindowsPath('/a/b').is_absolute()
      False
      >>> PureWindowsPath('c:').is_absolute()
      False
      >>> PureWindowsPath('//some/share').is_absolute()
      True

PurePath.is_reserved()

   With "PureWindowsPath", return "True" if the path is considered
   reserved under Windows, "False" otherwise.  With "PurePosixPath",
   "False" is always returned.

   >>> PureWindowsPath('nul').is_reserved()
   True
   >>> PurePosixPath('nul').is_reserved()
   False

   File system calls on reserved paths can fail mysteriously or have
   unintended effects.

PurePath.joinpath(*other)

   Calling this method is equivalent to combining the path with each
   of the *other* arguments in turn:

      >>> PurePosixPath('/etc').joinpath('passwd')
      PurePosixPath('/etc/passwd')
      >>> PurePosixPath('/etc').joinpath(PurePosixPath('passwd'))
      PurePosixPath('/etc/passwd')
      >>> PurePosixPath('/etc').joinpath('init.d', 'apache2')
      PurePosixPath('/etc/init.d/apache2')
      >>> PureWindowsPath('c:').joinpath('/Program Files')
      PureWindowsPath('c:/Program Files')

PurePath.match(pattern)

   Match this path against the provided glob-style pattern.  Return
   "True" if matching is successful, "False" otherwise.

   If *pattern* is relative, the path can be either relative or
   absolute, and matching is done from the right:

      >>> PurePath('a/b.py').match('*.py')
      True
      >>> PurePath('/a/b/c.py').match('b/*.py')
      True
      >>> PurePath('/a/b/c.py').match('a/*.py')
      False

   If *pattern* is absolute, the path must be absolute, and the whole
   path must match:

      >>> PurePath('/a.py').match('/*.py')
      True
      >>> PurePath('a/b.py').match('/*.py')
      False

   As with other methods, case-sensitivity is observed:

      >>> PureWindowsPath('b.py').match('*.PY')
      True

PurePath.relative_to(*other)

   Compute a version of this path relative to the path represented by
   *other*.  If it's impossible, ValueError is raised:

      >>> p = PurePosixPath('/etc/passwd')
      >>> p.relative_to('/')
      PurePosixPath('etc/passwd')
      >>> p.relative_to('/etc')
      PurePosixPath('passwd')
      >>> p.relative_to('/usr')
      Traceback (most recent call last):
        File "<stdin>", line 1, in <module>
        File "pathlib.py", line 694, in relative_to
          .format(str(self), str(formatted)))
      ValueError: '/etc/passwd' does not start with '/usr'

PurePath.with_name(name)

   Return a new path with the "name" changed.  If the original path
   doesn't have a name, ValueError is raised:

      >>> p = PureWindowsPath('c:/Downloads/pathlib.tar.gz')
      >>> p.with_name('setup.py')
      PureWindowsPath('c:/Downloads/setup.py')
      >>> p = PureWindowsPath('c:/')
      >>> p.with_name('setup.py')
      Traceback (most recent call last):
        File "<stdin>", line 1, in <module>
        File "/home/antoine/cpython/default/Lib/pathlib.py", line 751, in with_name
          raise ValueError("%r has an empty name" % (self,))
      ValueError: PureWindowsPath('c:/') has an empty name

PurePath.with_suffix(suffix)

   Return a new path with the "suffix" changed.  If the original path
   doesn't have a suffix, the new *suffix* is appended instead.  If
   the *suffix* is an empty string, the original suffix is removed:

      >>> p = PureWindowsPath('c:/Downloads/pathlib.tar.gz')
      >>> p.with_suffix('.bz2')
      PureWindowsPath('c:/Downloads/pathlib.tar.bz2')
      >>> p = PureWindowsPath('README')
      >>> p.with_suffix('.txt')
      PureWindowsPath('README.txt')
      >>> p = PureWindowsPath('README.txt')
      >>> p.with_suffix('')
      PureWindowsPath('README')


Concrete paths
==============

Concrete paths are subclasses of the pure path classes.  In addition
to operations provided by the latter, they also provide methods to do
system calls on path objects.  There are three ways to instantiate
concrete paths:

class pathlib.Path(*pathsegments)

   A subclass of "PurePath", this class represents concrete paths of
   the system's path flavour (instantiating it creates either a
   "PosixPath" or a "WindowsPath"):

      >>> Path('setup.py')
      PosixPath('setup.py')

   *pathsegments* is specified similarly to "PurePath".

class pathlib.PosixPath(*pathsegments)

   A subclass of "Path" and "PurePosixPath", this class represents
   concrete non-Windows filesystem paths:

      >>> PosixPath('/etc')
      PosixPath('/etc')

   *pathsegments* is specified similarly to "PurePath".

class pathlib.WindowsPath(*pathsegments)

   A subclass of "Path" and "PureWindowsPath", this class represents
   concrete Windows filesystem paths:

      >>> WindowsPath('c:/Program Files/')
      WindowsPath('c:/Program Files')

   *pathsegments* is specified similarly to "PurePath".

You can only instantiate the class flavour that corresponds to your
system (allowing system calls on non-compatible path flavours could
lead to bugs or failures in your application):

   >>> import os
   >>> os.name
   'posix'
   >>> Path('setup.py')
   PosixPath('setup.py')
   >>> PosixPath('setup.py')
   PosixPath('setup.py')
   >>> WindowsPath('setup.py')
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "pathlib.py", line 798, in __new__
       % (cls.__name__,))
   NotImplementedError: cannot instantiate 'WindowsPath' on your system


Methods
-------

Concrete paths provide the following methods in addition to pure paths
methods.  Many of these methods can raise an "OSError" if a system
call fails (for example because the path doesn't exist).

3.8 版更變: "exists()", "is_dir()", "is_file()", "is_mount()",
"is_symlink()", "is_block_device()", "is_char_device()", "is_fifo()",
"is_socket()" now return "False" instead of raising an exception for
paths that contain characters unrepresentable at the OS level.

classmethod Path.cwd()

   Return a new path object representing the current directory (as
   returned by "os.getcwd()"):

      >>> Path.cwd()
      PosixPath('/home/antoine/pathlib')

classmethod Path.home()

   Return a new path object representing the user's home directory (as
   returned by "os.path.expanduser()" with "~" construct):

      >>> Path.home()
      PosixPath('/home/antoine')

   3.5 版新加入.

Path.stat()

   Return information about this path (similarly to "os.stat()"). The
   result is looked up at each call to this method.

      >>> p = Path('setup.py')
      >>> p.stat().st_size
      956
      >>> p.stat().st_mtime
      1327883547.852554

Path.chmod(mode)

   Change the file mode and permissions, like "os.chmod()":

      >>> p = Path('setup.py')
      >>> p.stat().st_mode
      33277
      >>> p.chmod(0o444)
      >>> p.stat().st_mode
      33060

Path.exists()

   Whether the path points to an existing file or directory:

      >>> Path('.').exists()
      True
      >>> Path('setup.py').exists()
      True
      >>> Path('/etc').exists()
      True
      >>> Path('nonexistentfile').exists()
      False

   備註: If the path points to a symlink, "exists()" returns whether
     the symlink *points to* an existing file or directory.

Path.expanduser()

   Return a new path with expanded "~" and "~user" constructs, as
   returned by "os.path.expanduser()":

      >>> p = PosixPath('~/films/Monty Python')
      >>> p.expanduser()
      PosixPath('/home/eric/films/Monty Python')

   3.5 版新加入.

Path.glob(pattern)

   解析相对于此路径的通配符 *pattern*，产生所有匹配的文件:

      >>> sorted(Path('.').glob('*.py'))
      [PosixPath('pathlib.py'), PosixPath('setup.py'), PosixPath('test_pathlib.py')]
      >>> sorted(Path('.').glob('*/*.py'))
      [PosixPath('docs/conf.py')]

   The ""**"" pattern means "this directory and all subdirectories,
   recursively".  In other words, it enables recursive globbing:

      >>> sorted(Path('.').glob('**/*.py'))
      [PosixPath('build/lib/pathlib.py'),
       PosixPath('docs/conf.py'),
       PosixPath('pathlib.py'),
       PosixPath('setup.py'),
       PosixPath('test_pathlib.py')]

   備註: Using the ""**"" pattern in large directory trees may
     consume an inordinate amount of time.

Path.group()

   Return the name of the group owning the file.  "KeyError" is raised
   if the file's gid isn't found in the system database.

Path.is_dir()

   Return "True" if the path points to a directory (or a symbolic link
   pointing to a directory), "False" if it points to another kind of
   file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.is_file()

   Return "True" if the path points to a regular file (or a symbolic
   link pointing to a regular file), "False" if it points to another
   kind of file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.is_mount()

   Return "True" if the path is a *mount point*: a point in a file
   system where a different file system has been mounted.  On POSIX,
   the function checks whether *path*'s parent, "path/..", is on a
   different device than *path*, or whether "path/.." and *path* point
   to the same i-node on the same device --- this should detect mount
   points for all Unix and POSIX variants.  Not implemented on
   Windows.

   3.7 版新加入.

Path.is_symlink()

   Return "True" if the path points to a symbolic link, "False"
   otherwise.

   "False" is also returned if the path doesn't exist; other errors
   (such as permission errors) are propagated.

Path.is_socket()

   Return "True" if the path points to a Unix socket (or a symbolic
   link pointing to a Unix socket), "False" if it points to another
   kind of file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.is_fifo()

   Return "True" if the path points to a FIFO (or a symbolic link
   pointing to a FIFO), "False" if it points to another kind of file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.is_block_device()

   Return "True" if the path points to a block device (or a symbolic
   link pointing to a block device), "False" if it points to another
   kind of file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.is_char_device()

   Return "True" if the path points to a character device (or a
   symbolic link pointing to a character device), "False" if it points
   to another kind of file.

   "False" is also returned if the path doesn't exist or is a broken
   symlink; other errors (such as permission errors) are propagated.

Path.iterdir()

   When the path points to a directory, yield path objects of the
   directory contents:

      >>> p = Path('docs')
      >>> for child in p.iterdir(): child
      ...
      PosixPath('docs/conf.py')
      PosixPath('docs/_templates')
      PosixPath('docs/make.bat')
      PosixPath('docs/index.rst')
      PosixPath('docs/_build')
      PosixPath('docs/_static')
      PosixPath('docs/Makefile')

Path.lchmod(mode)

   Like "Path.chmod()" but, if the path points to a symbolic link, the
   symbolic link's mode is changed rather than its target's.

Path.lstat()

   Like "Path.stat()" but, if the path points to a symbolic link,
   return the symbolic link's information rather than its target's.

Path.mkdir(mode=0o777, parents=False, exist_ok=False)

   Create a new directory at this given path.  If *mode* is given, it
   is combined with the process' "umask" value to determine the file
   mode and access flags.  If the path already exists,
   "FileExistsError" is raised.

   If *parents* is true, any missing parents of this path are created
   as needed; they are created with the default permissions without
   taking *mode* into account (mimicking the POSIX "mkdir -p"
   command).

   If *parents* is false (the default), a missing parent raises
   "FileNotFoundError".

   If *exist_ok* is false (the default), "FileExistsError" is raised
   if the target directory already exists.

   If *exist_ok* is true, "FileExistsError" exceptions will be ignored
   (same behavior as the POSIX "mkdir -p" command), but only if the
   last path component is not an existing non-directory file.

   3.5 版更變: The *exist_ok* parameter was added.

Path.open(mode='r', buffering=-1, encoding=None, errors=None, newline=None)

   Open the file pointed to by the path, like the built-in "open()"
   function does:

      >>> p = Path('setup.py')
      >>> with p.open() as f:
      ...     f.readline()
      ...
      '#!/usr/bin/env python3\n'

Path.owner()

   Return the name of the user owning the file.  "KeyError" is raised
   if the file's uid isn't found in the system database.

Path.read_bytes()

   Return the binary contents of the pointed-to file as a bytes
   object:

      >>> p = Path('my_binary_file')
      >>> p.write_bytes(b'Binary file contents')
      20
      >>> p.read_bytes()
      b'Binary file contents'

   3.5 版新加入.

Path.read_text(encoding=None, errors=None)

   Return the decoded contents of the pointed-to file as a string:

      >>> p = Path('my_text_file')
      >>> p.write_text('Text file contents')
      18
      >>> p.read_text()
      'Text file contents'

   The file is opened and then closed. The optional parameters have
   the same meaning as in "open()".

   3.5 版新加入.

Path.rename(target)

   Rename this file or directory to the given *target*.  On Unix, if
   *target* exists and is a file, it will be replaced silently if the
   user has permission.  *target* can be either a string or another
   path object:

      >>> p = Path('foo')
      >>> p.open('w').write('some text')
      9
      >>> target = Path('bar')
      >>> p.rename(target)
      >>> target.open().read()
      'some text'

Path.replace(target)

   Rename this file or directory to the given *target*.  If *target*
   points to an existing file or directory, it will be unconditionally
   replaced.

Path.resolve(strict=False)

   Make the path absolute, resolving any symlinks.  A new path object
   is returned:

      >>> p = Path()
      >>> p
      PosixPath('.')
      >>> p.resolve()
      PosixPath('/home/antoine/pathlib')

   "".."" components are also eliminated (this is the only method to
   do so):

      >>> p = Path('docs/../setup.py')
      >>> p.resolve()
      PosixPath('/home/antoine/pathlib/setup.py')

   If the path doesn't exist and *strict* is "True",
   "FileNotFoundError" is raised.  If *strict* is "False", the path is
   resolved as far as possible and any remainder is appended without
   checking whether it exists.  If an infinite loop is encountered
   along the resolution path, "RuntimeError" is raised.

   3.6 版新加入: 加入*strict* 参数（3.6之前的版本相当于strict值为True
   ）

Path.rglob(pattern)

   这就像调用 "Path.glob`时在给定的相对 *pattern* 前面添加了
   "``**/`()""

      >>> sorted(Path().rglob("*.py"))
      [PosixPath('build/lib/pathlib.py'),
       PosixPath('docs/conf.py'),
       PosixPath('pathlib.py'),
       PosixPath('setup.py'),
       PosixPath('test_pathlib.py')]

Path.rmdir()

   Remove this directory.  The directory must be empty.

Path.samefile(other_path)

   Return whether this path points to the same file as *other_path*,
   which can be either a Path object, or a string.  The semantics are
   similar to "os.path.samefile()" and "os.path.samestat()".

   An "OSError" can be raised if either file cannot be accessed for
   some reason.

      >>> p = Path('spam')
      >>> q = Path('eggs')
      >>> p.samefile(q)
      False
      >>> p.samefile('spam')
      True

   3.5 版新加入.

Path.symlink_to(target, target_is_directory=False)

   Make this path a symbolic link to *target*.  Under Windows,
   *target_is_directory* must be true (default "False") if the link's
   target is a directory.  Under POSIX, *target_is_directory*'s value
   is ignored.

      >>> p = Path('mylink')
      >>> p.symlink_to('setup.py')
      >>> p.resolve()
      PosixPath('/home/antoine/pathlib/setup.py')
      >>> p.stat().st_size
      956
      >>> p.lstat().st_size
      8

   備註: The order of arguments (link, target) is the reverse of
     "os.symlink()"'s.

Path.touch(mode=0o666, exist_ok=True)

   Create a file at this given path.  If *mode* is given, it is
   combined with the process' "umask" value to determine the file mode
   and access flags.  If the file already exists, the function
   succeeds if *exist_ok* is true (and its modification time is
   updated to the current time), otherwise "FileExistsError" is
   raised.

Path.unlink(missing_ok=False)

   Remove this file or symbolic link.  If the path points to a
   directory, use "Path.rmdir()" instead.

   If *missing_ok* is false (the default), "FileNotFoundError" is
   raised if the path does not exist.

   If *missing_ok* is true, "FileNotFoundError" exceptions will be
   ignored (same behavior as the POSIX "rm -f" command).

   3.8 版更變: The *missing_ok* parameter was added.

Path.link_to(target)

   Create a hard link pointing to a path named *target*.

   3.8 版更變.

Path.write_bytes(data)

   Open the file pointed to in bytes mode, write *data* to it, and
   close the file:

      >>> p = Path('my_binary_file')
      >>> p.write_bytes(b'Binary file contents')
      20
      >>> p.read_bytes()
      b'Binary file contents'

   An existing file of the same name is overwritten.

   3.5 版新加入.

Path.write_text(data, encoding=None, errors=None)

   Open the file pointed to in text mode, write *data* to it, and
   close the file:

      >>> p = Path('my_text_file')
      >>> p.write_text('Text file contents')
      18
      >>> p.read_text()
      'Text file contents'

   3.5 版新加入.


Correspondence to tools in the "os" module
==========================================

Below is a table mapping various "os" functions to their corresponding
"PurePath"/"Path" equivalent.

備註: Although "os.path.relpath()" and "PurePath.relative_to()" have
  some overlapping use-cases, their semantics differ enough to warrant
  not considering them equivalent.

+--------------------------------------+--------------------------------+
| os and os.path                       | pathlib                        |
|======================================|================================|
| "os.path.abspath()"                  | "Path.resolve()"               |
+--------------------------------------+--------------------------------+
| "os.chmod()"                         | "Path.chmod()"                 |
+--------------------------------------+--------------------------------+
| "os.mkdir()"                         | "Path.mkdir()"                 |
+--------------------------------------+--------------------------------+
| "os.rename()"                        | "Path.rename()"                |
+--------------------------------------+--------------------------------+
| "os.replace()"                       | "Path.replace()"               |
+--------------------------------------+--------------------------------+
| "os.rmdir()"                         | "Path.rmdir()"                 |
+--------------------------------------+--------------------------------+
| "os.remove()", "os.unlink()"         | "Path.unlink()"                |
+--------------------------------------+--------------------------------+
| "os.getcwd()"                        | "Path.cwd()"                   |
+--------------------------------------+--------------------------------+
| "os.path.exists()"                   | "Path.exists()"                |
+--------------------------------------+--------------------------------+
| "os.path.expanduser()"               | "Path.expanduser()" and        |
|                                      | "Path.home()"                  |
+--------------------------------------+--------------------------------+
| "os.path.isdir()"                    | "Path.is_dir()"                |
+--------------------------------------+--------------------------------+
| "os.path.isfile()"                   | "Path.is_file()"               |
+--------------------------------------+--------------------------------+
| "os.path.islink()"                   | "Path.is_symlink()"            |
+--------------------------------------+--------------------------------+
| "os.stat()"                          | "Path.stat()", "Path.owner()", |
|                                      | "Path.group()"                 |
+--------------------------------------+--------------------------------+
| "os.path.isabs()"                    | "PurePath.is_absolute()"       |
+--------------------------------------+--------------------------------+
| "os.path.join()"                     | "PurePath.joinpath()"          |
+--------------------------------------+--------------------------------+
| "os.path.basename()"                 | "PurePath.name"                |
+--------------------------------------+--------------------------------+
| "os.path.dirname()"                  | "PurePath.parent"              |
+--------------------------------------+--------------------------------+
| "os.path.samefile()"                 | "Path.samefile()"              |
+--------------------------------------+--------------------------------+
| "os.path.splitext()"                 | "PurePath.suffix"              |
+--------------------------------------+--------------------------------+
