Add toml python extra to pull in a toml parser

README.md

@@ -27,6 +27,14 @@ It can be installed with pip:
 
     pip install antsibull-changelog
 
+For python projects, `antsibull-changelog release` can retrieve the current
+version from `pyproject.toml`.
+You can install the project with
+
+    pip install antsibull-changelog[toml]
+
+to pull in the necessary toml parser for this feature.
+
 For more information, see the
 [documentation](https://github.com/ansible-community/antsibull-changelog/tree/main/docs/changelogs.rst).
 

changelogs/fragments/126-toml-extra.yaml

@@ -0,0 +1,5 @@
+---
+minor_changes:
+  - Add ``toml`` extra to pull in a toml parser to use to guess the version
+    based on ``pyproject.toml``
+    (https://github.com/ansible-community/antsibull-changelog/pull/126).

pyproject.toml

@@ -53,6 +53,19 @@ antsibull-changelog = "antsibull_changelog.cli:main"
 
 
 [project.optional-dependencies]
+#
+# User facing
+#
+
+# Use for getting the current version from pyproject.toml
+toml = [
+    "tomli; python_version<'3.11'",
+]
+
+#
+# Development. Not user facing.
+#
+
 codeqa = [
     "flake8 >= 3.8.0",
     "pylint",