gh-137353: Add t-string support to gettext + pygettext #137354

ThiefMaster · 2025-08-03T19:04:35Z

Please see #137353 for details; TL;DR is that with this PR you can use t-strings for i18n, instead of having to call _(...).format(...)

print(_(t'Hello {name}'))
print(ngettext(t'{n} snake', t'{n} snakes', n))
print(_(t'Category "{cat.title}" moved to "{target_cat.title}"'))

Issue: Support t-strings in gettext #137353

python-cla-bot · 2025-08-03T19:04:40Z

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bedevere-app · 2025-08-03T19:04:40Z

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StanFromIreland

Please split this into separate PRs for pygettext and gettext. They also need blurbs.

ThiefMaster · 2025-08-03T19:14:46Z

There would be some overlap between the two PRs, since parts of the code are required both for gettext and pygettext.

Do you still prefer having two separate PRs even in this early stage? I can do it of course, but my preference would be splitting it later, once any discussions that may come up are resolved and I made whatever changes may be necessary...

bedevere-app · 2025-08-03T19:15:01Z

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

StanFromIreland · 2025-08-03T19:15:58Z

Lib/gettext.py

+
+
+# utils for t-string handling in gettext translation + pygettext extraction
+# TBD where they should go, and whether this should be a public API or internal,


I think we should limit what is exposed in gettext apart from the core API.

Yeah, that's why I underscored all of them for now.

FWIW, I think exposing at least the utils to convert a template string to a format string makes sense, because tools like Babel would need to use the exact same logic, or risk inconsistencies between implementations.

StanFromIreland · 2025-08-03T19:18:09Z

Lib/gettext.py

+# beneficial to have in stdlib so any implementation can re-use it without
+# risking diverging behavior for the same expression between implementations
+
+class _NameTooComplexError(ValueError):


This however should be IMO documented, since it is “public”. I however don’t like this, I think a general (new) gettext error (or, much simpler, a ValueError) would be clearer, thoughts, Tomas?

Initially I just used this to avoid catching some other (unexpected) ValueError that may or may not come out of the ast visitor. A custom exception just for this may indeed be overkill.

But I like the idea of a GettextError :)

StanFromIreland · 2025-08-03T19:18:54Z

Lib/gettext.py

+def _template_node_to_format(node: ast.TemplateStr) -> str:
+    """Generate a format string from a template string AST node.
+
+    This fails with a :exc:`_NameTooComplexError` in case the expression is


Docstrings are not restructured text in CPython.

updated, lmk in case you don't like backticks around class names etc

StanFromIreland · 2025-08-03T19:20:16Z

Lib/test/test_gettext.py

@@ -38,6 +38,27 @@
 bmsgd2luayAoaW4gIm15IG90aGVyIGNvbnRleHQiKQB3aW5rIHdpbmsA
 '''

+GNU_TMO_DATA = b'''\


It’s not a particularly clear name IMO.

Agreed, I just stayed consistent w/ the existing ones. Updated to something more meaningful.

StanFromIreland · 2025-08-03T19:24:03Z

We generally tend to avoid mixing large changes to different modules (tool in this case) as it makes the PR much larger.

Also, please avoid force pushing, gh is unable to distinguish differences between them.

ThiefMaster · 2025-08-03T19:57:15Z

Lib/test/test_tools/i18n_data/messages.py

+_(t'Weird {meow[69j]}')
+_(t'Weird {meow[...]}')


FWIW I think these two are stupid and will never be used, but I didn't see much value in adding an extra check for certain type of Constant values to just to avoid those.

ThiefMaster · 2025-08-03T20:00:08Z

Lib/gettext.py

+
+    @property
+    def name(self) -> str:
+        name = '__'.join(self._name_parts)


I used __ as a separator between parts since initially I thought that it might be nice to make it clearer that the placeholder for {user.name} isn't just something named user_name.

However, maybe using a single underscore would be fine here:

t'{user.name} {user_name}' would simply fail due to the check that a name doesn't map to different expressions

I can't come up with a good example where you would use foo.bar and foo_bar in the same string

ThiefMaster · 2025-08-03T20:01:35Z

Lib/test/test_gettext.py

+        # We use this weird naming of the gettext functions here to allow
+        # easy extraction of the .po file using pygettext; see the comment
+        # next to the po file content near the bottom of this file on how
+        # to regenerate it.
+        self.gettexT = self.t.gettext
+        self.ngettexT = self.t.ngettext
+        self.pgettexT = self.t.pgettext
+        self.npgettexT = self.t.npgettext


I don't expect to keep these weird names, but for the sake of making it easier to update the tests in the future, I'd probably go for something like t_gettext etc. in here.

ThiefMaster · 2025-08-03T20:03:19Z

Also, please avoid force pushing, gh is unable to distinguish differences between them.

OK, will keep this in mind for future changes.

ThiefMaster requested a review from tomasr8 as a code owner August 3, 2025 19:04

bedevere-app bot added the awaiting review label Aug 3, 2025

bedevere-app bot mentioned this pull request Aug 3, 2025

Support t-strings in gettext #137353

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StanFromIreland reviewed Aug 3, 2025

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ThiefMaster force-pushed the gettext-tstrings branch from 0d75d3c to 2b7fa77 Compare August 3, 2025 19:14

StanFromIreland reviewed Aug 3, 2025

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ThiefMaster force-pushed the gettext-tstrings branch from 2b7fa77 to 665ae49 Compare August 3, 2025 19:22

Add support for t-string gettext extraction

e42a9ae

ThiefMaster force-pushed the gettext-tstrings branch from 665ae49 to 23ad71a Compare August 3, 2025 19:29

Add support for t-string gettext translation

d603887

ThiefMaster force-pushed the gettext-tstrings branch from 23ad71a to d603887 Compare August 3, 2025 19:32

ThiefMaster commented Aug 3, 2025

View reviewed changes

ThiefMaster mentioned this pull request Aug 3, 2025

Support t-strings in Python 3.14 python-babel/babel#1206

Open



		# utils for t-string handling in gettext translation + pygettext extraction
		# TBD where they should go, and whether this should be a public API or internal,

		_(t'Weird {meow[69j]}')
		_(t'Weird {meow[...]}')

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gh-137353: Add t-string support to gettext + pygettext #137354

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gh-137353: Add t-string support to gettext + pygettext #137354

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ThiefMaster commented Aug 3, 2025

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