Use the class under test to create files, directories and symlinks.

…ther.

This is a very soft deprecation of `PurePath.as_uri()`. We instead document
it as a `Path` method, and add a couple of sentences mentioning that it's
also available in `PurePath`.

Add `PurePathBase` and `PathBase` abstract base classes.

`PathBase` can be subclassed to implement *virtual paths*: objects
representing paths on virtual filesystems, like archive files or remote
storage systems.

- Add fast path to `_split_stack()`
- Skip unnecessarily resolution of the current directory when a relative
  path is given to `resolve()`
- Remove stat and target caches, which slow down most `resolve()` calls in
  practice.
- Slightly refactor code for clarity.

Use the class under test to create files, directories and symlinks.

…classes.

This adds some test coverage to `pathlib._PathBase.walk()`

Add private `pathlib._PurePathBase` class: a private superclass of both
`PurePath` and `_PathBase`. Unlike `PurePath`, it does not define any of
these special methods: `__fspath__`, `__bytes__`, `__reduce__`, `__hash__`,
`__eq__`, `__lt__`, `__le__`, `__gt__`, `__ge__`.

This is important for supporting *virtual paths*: user subclasses of
`_PathBase` that provide access to archive files, FTP servers, etc. In
these classes, the above methods should be implemented by users only as
appropriate, with due consideration for the hash/equality of any backing
objects, such as file objects or sockets.

…s. (#110655)

…classes. (python#110655)

Re-arrange `pathlib.PurePath` methods in source code. No other changes.

The `PurePath` implementations of certain special methods, such as
`__eq__()` and `__hash__()`, are not usually applicable to user subclasses
of `_PathBase`. To facilitate their removal, another patch will split the
`PurePath` class into `_PurePathBase` and `PurePath`, with the latter
providing these special methods.

This patch prepares the ground for splitting `PurePath`. It's similar to
e8d77b0, which preceded splitting `Path`. By churning the methods here,
subsequent patches will be easier to review and less likely to break
things.

Change the value of `pathlib._abc.PurePathBase.pathmod` from `os.path` to
`posixpath`.

User subclasses of `PurePathBase` and `PathBase` previously used the host
OS's path syntax, e.g. backslashes as separators on Windows. This is wrong
in most use cases, and likely to catch developers out unless they test on
both Windows and non-Windows machines.

In this patch we change the default to POSIX syntax, regardless of OS. This
is somewhat arguable (why not make all aspects of syntax abstract and
individually configurable?) but an improvement all the same.

This change has no effect on `PurePath`, `Path`, nor their subclasses. Only
private APIs are affected.

…tribute

Store the test base directory as a class attribute named `base` rather than
module constants named `BASE`.

The base directory is a local file path, and therefore not ideally suited
to the pathlib ABC tests. In a future commit we'll change its value in
`test_pathlib_abc.py` such that it points to a totally fictitious path.

#113221)

Store the test base directory as a class attribute named `base` rather than
module constants named `BASE`.

The base directory is a local file path, and therefore not ideally suited
to the pathlib ABC tests. In a future commit we'll change its value in
`test_pathlib_abc.py` such that it points to a totally fictitious path, which 
will help to ensure we're not touching the local filesystem.

A regex group with a `?+` possessive quantifier was used to match empty
paths, which were represented as a single dot, preventing the dot from
being matched by other wildcards. This quantifier is only available from
Python 3.11+, but pathlib's `_abc.py` file will be made available as a PyPI
package for Python 3.8+.

This commit adds a new private `_pattern_str` property that works like
`__str__()` but represents empty paths as `''` rather than `'.'`. This
string is used for pattern matching, which removes the need for the
possessive group.

Improves compatibility with older Python; no other change of behaviour.

`PurePathBase.__repr__()` produces a string like `MyPath('/foo')`. This
repr is incorrect/misleading when a subclass's `__init__()` method is
customized, which I expect to be the very common.

This commit moves the `__repr__()` method to `PurePath`, leaving
`PurePathBase` with the default `object` repr.

No user-facing changes because the `pathlib._abc` module remains private.

`PurePathBase.__repr__()` produces a string like `MyPath('/foo')`. This
repr is incorrect/misleading when a subclass's `__init__()` method is
customized, which I expect to be the very common.

This commit moves the `__repr__()` method to `PurePath`, leaving
`PurePathBase` with the default `object` repr.

No user-facing changes because the `pathlib._abc` module remains private.

Change the value of `pathlib._abc.PurePathBase.pathmod` from `os.path` to
`posixpath`.

User subclasses of `PurePathBase` and `PathBase` previously used the host
OS's path syntax, e.g. backslashes as separators on Windows. This is wrong
in most use cases, and likely to catch developers out unless they test on
both Windows and non-Windows machines.

In this patch we change the default to POSIX syntax, regardless of OS. This
is somewhat arguable (why not make all aspects of syntax abstract and
individually configurable?) but an improvement all the same.

This change has no effect on `PurePath`, `Path`, nor their subclasses. Only
private APIs are affected.

This very boring patch reduces the number of changes needed in
`test_pathlib_abc.py` when backporting to the external `pathlib_abc`
package.

…3411)

This very boring patch reduces the number of changes needed in
`test_pathlib_abc.py` when backporting to the external `pathlib_abc`
package.

Do not use the locale-specific default encoding in `PathBase.read_text()`
and `write_text()`. Locale settings shouldn't influence the operation of
these base classes, which are intended mostly for implementing rich paths
on *nonlocal* filesystems.

Do not use the locale-specific default encoding in `PathBase.read_text()`
and `write_text()`. Locale settings shouldn't influence the operation of
these base classes, which are intended mostly for implementing rich paths
on *nonlocal* filesystems.

The `pathlib._abc` module will be made available as a PyPI backport
supporting Python 3.8+. The `warnings._deprecated()` function was only
added last year, and it's private from an external package perspective, so
here we switch to `warnings.warn()` instead.

…hon#113376)

`PurePathBase.__repr__()` produces a string like `MyPath('/foo')`. This
repr is incorrect/misleading when a subclass's `__init__()` method is
customized, which I expect to be the very common.

This commit moves the `__repr__()` method to `PurePath`, leaving
`PurePathBase` with the default `object` repr.

No user-facing changes because the `pathlib._abc` module remains private.

…ython#113219)

Change the value of `pathlib._abc.PurePathBase.pathmod` from `os.path` to
`posixpath`.

User subclasses of `PurePathBase` and `PathBase` previously used the host
OS's path syntax, e.g. backslashes as separators on Windows. This is wrong
in most use cases, and likely to catch developers out unless they test on
both Windows and non-Windows machines.

In this patch we change the default to POSIX syntax, regardless of OS. This
is somewhat arguable (why not make all aspects of syntax abstract and
individually configurable?) but an improvement all the same.

This change has no effect on `PurePath`, `Path`, nor their subclasses. Only
private APIs are affected.

python#113411)

This very boring patch reduces the number of changes needed in
`test_pathlib_abc.py` when backporting to the external `pathlib_abc`
package.

Do not use the locale-specific default encoding in `PathBase.read_text()`
and `write_text()`. Locale settings shouldn't influence the operation of
these base classes, which are intended mostly for implementing rich paths
on *nonlocal* filesystems.

The `pathlib._abc` module will be made available as a PyPI backport
supporting Python 3.8+. The `warnings._deprecated()` function was only
added last year, and it's private from an external package perspective, so
here we switch to `warnings.warn()` instead.