cpython/Doc/library/tomllib.rst
Taneli Hukkinen 591f6754b5
bpo-40059: Add tomllib (PEP-680) (GH-31498)
This adds a new standard library module, `tomllib`, for parsing TOML.

The implementation is based on Tomli (https://github.com/hukkin/tomli).

## Steps taken (converting `tomli` to `tomllib`)

- Move everything in `tomli:src/tomli` to `Lib/tomllib`. Exclude `py.typed`.
- Remove `__version__ = ...` line from `Lib/tomllib/__init__.py`
- Move everything in `tomli:tests` to `Lib/test/test_tomllib`. Exclude the following test data dirs recursively:
  - `tomli:tests/data/invalid/_external/`
  - `tomli:tests/data/valid/_external/`
- Create `Lib/test/test_tomllib/__main__.py`:

  ```python
  import unittest

  from . import load_tests


  unittest.main()
  ```


- Add the following to `Lib/test/test_tomllib/__init__.py`:

  ```python
  import os
  from test.support import load_package_tests

  def load_tests(*args):
      return load_package_tests(os.path.dirname(__file__), *args)
  ```

  Also change `import tomli as tomllib` to `import tomllib`.

- In `cpython/Lib/tomllib/_parser.py` replace `__fp` with `fp` and `__s` with
  `s`. Add the `/` to `load` and `loads` function signatures.

- Run `make regen-stdlib-module-names`

- Create `Doc/library/tomllib.rst` and reference it in `Doc/library/fileformats.rst`
2022-03-08 09:26:13 +01:00

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:mod:`tomllib` --- Parse TOML files
===================================
.. module:: tomllib
:synopsis: Parse TOML files.
.. versionadded:: 3.11
.. moduleauthor:: Taneli Hukkinen
.. sectionauthor:: Taneli Hukkinen
**Source code:** :source:`Lib/tomllib`
--------------
This module provides an interface for parsing TOML (Tom's Obvious Minimal
Language, `https://toml.io <https://toml.io/en/>`_). This module does not
support writing TOML.
.. seealso::
The `Tomli-W package <https://pypi.org/project/tomli-w/>`__
is a TOML writer that can be used in conjunction with this module,
providing a write API familiar to users of the standard library
:mod:`marshal` and :mod:`pickle` modules.
.. seealso::
The `TOML Kit package <https://pypi.org/project/tomlkit/>`__
is a style-preserving TOML library with both read and write capability.
It is a recommended replacement for this module for editing already
existing TOML files.
This module defines the following functions:
.. function:: load(fp, /, *, parse_float=float)
Read a TOML file. The first argument should be a readable and binary file object.
Return a :class:`dict`. Convert TOML types to Python using this
:ref:`conversion table <toml-to-py-table>`.
*parse_float* will be called with the string of every TOML
float to be decoded. By default, this is equivalent to ``float(num_str)``.
This can be used to use another datatype or parser for TOML floats
(e.g. :class:`decimal.Decimal`). The callable must not return a
:class:`dict` or a :class:`list`, else a :exc:`ValueError` is raised.
A :exc:`TOMLDecodeError` will be raised on an invalid TOML document.
.. function:: loads(s, /, *, parse_float=float)
Load TOML from a :class:`str` object. Return a :class:`dict`. Convert TOML
types to Python using this :ref:`conversion table <toml-to-py-table>`. The
*parse_float* argument has the same meaning as in :func:`load`.
A :exc:`TOMLDecodeError` will be raised on an invalid TOML document.
The following exceptions are available:
.. exception:: TOMLDecodeError
Subclass of :exc:`ValueError`.
Examples
--------
Parsing a TOML file::
import tomllib
with open("pyproject.toml", "rb") as f:
data = tomllib.load(f)
Parsing a TOML string::
import tomllib
toml_str = """
python-version = "3.11.0"
python-implementation = "CPython"
"""
data = tomllib.loads(toml_str)
Conversion Table
----------------
.. _toml-to-py-table:
+------------------+--------------------------------------------------------------------------------------+
| TOML | Python |
+==================+======================================================================================+
| table | dict |
+------------------+--------------------------------------------------------------------------------------+
| string | str |
+------------------+--------------------------------------------------------------------------------------+
| integer | int |
+------------------+--------------------------------------------------------------------------------------+
| float | float (configurable with *parse_float*) |
+------------------+--------------------------------------------------------------------------------------+
| boolean | bool |
+------------------+--------------------------------------------------------------------------------------+
| offset date-time | datetime.datetime (``tzinfo`` attribute set to an instance of ``datetime.timezone``) |
+------------------+--------------------------------------------------------------------------------------+
| local date-time | datetime.datetime (``tzinfo`` attribute set to ``None``) |
+------------------+--------------------------------------------------------------------------------------+
| local date | datetime.date |
+------------------+--------------------------------------------------------------------------------------+
| local time | datetime.time |
+------------------+--------------------------------------------------------------------------------------+
| array | list |
+------------------+--------------------------------------------------------------------------------------+