https://github.com/python/cpython/commit/880c9526f91960b9cba557a18b54e2c32d2f254e commit: 880c9526f91960b9cba557a18b54e2c32d2f254e branch: main author: Dave Peck <[email protected]> committer: AA-Turner <[email protected]> date: 2025-10-04T22:06:56+01:00 summary:
gh-138558: Improve description of ``Interpolation.expression`` (#139187) Co-authored-by: Adam Turner <[email protected]> files: M Doc/library/string.templatelib.rst diff --git a/Doc/library/string.templatelib.rst b/Doc/library/string.templatelib.rst index 85d65fa9de1e22..a5b2d796aaf4b8 100644 --- a/Doc/library/string.templatelib.rst +++ b/Doc/library/string.templatelib.rst @@ -24,7 +24,7 @@ Template strings Template strings are a mechanism for custom string processing. They have the full flexibility of Python's :ref:`f-strings`, but return a :class:`Template` instance that gives access -to the static and interpolated (in curly braces) parts of a string +to the static and interpolated (in curly brackets) parts of a string *before* they are combined. To write a t-string, use a ``'t'`` prefix instead of an ``'f'``, like so: @@ -258,13 +258,16 @@ Types .. attribute:: expression :type: str - The text of a valid Python expression, or an empty string. + For interpolations created by t-string literals, :attr:`!expression` + is the expression text found inside the curly brackets (``{`` & ``}``), + including any whitespace, excluding the curly brackets themselves, + and ending before the first ``!``, ``:``, or ``=`` if any is present. + For manually created interpolations, :attr:`!expression` is the arbitrary + string provided when constructing the interpolation instance. - The :attr:`.expression` is the original text of the - interpolation's Python expression, if the interpolation was created - from a t-string literal. Developers creating interpolations manually - should either set this to an empty string or choose a suitable valid - Python expression. + We recommend using valid Python expressions or the empty string for the + ``expression`` field of manually created :class:`!Interpolation` + instances, although this is not enforced at runtime. >>> t'{1 + 2}'.interpolations[0].expression '1 + 2' _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
