Description

loic-simon

opened on May 22, 2025

Issue body actions

Feature or enhancement

Proposal:

Update pprint functions to understand and format Template and Interpolation types:

>>> from pprint import pp
>>> name = "World"
>>> pp(t"Hello {name}")
Template(strings=('Hello ', ''),
         interpolations=(Interpolation('World', 'name', None, ''),))""")

I believe it will be quite common to play with t-strings in the REPL and other dynamic environments, where pretty formatting could help a lot. I don't know how high is the bar for adding types to the pprint registry, though.

If this is deemed worthwhile, I have a working implementation, pretty straightforward.

---

More complex examples (inspired from the PEP), to give a sense of what it could look like:

>>> attributes = {"id": "main"}
>>> attribute_value = "shrubbery"
>>> content = "hello"
>>> template = t"<span {attributes} data-value={attribute_value}>{content}</span>"
>>> pp(template)
Template(strings=('<span ', ' data-value=', '>', '</span>'),
         interpolations=(Interpolation({'id': 'main'}, 'attributes', None, ''),
                         Interpolation('shrubbery',
                                       'attribute_value',
                                       None,
                                       ''),
                         Interpolation('hello', 'content', None, '')))
>>>
>>> nested = t"<div>{template}</div>"
>>> pp(nested)
Template(strings=('<div>', '</div>'),
         interpolations=(Interpolation(Template(strings=('<span ',
                                                         ' data-value=',
                                                         '>',
                                                         '</span>'),
                                                interpolations=(Interpolation({'id': 'main'},
                                                                              'attributes',
                                                                              None,
                                                                              ''),
                                                                Interpolation('shrubbery',
                                                                              'attribute_value',
                                                                              None,
                                                                              ''),
                                                                Interpolation('hello',
                                                                              'content',
                                                                              None,
                                                                              ''))),
                                       'template',
                                       None,
                                       ''),))

Unfortunately, "interpolation" being a quite long word repeated 2 times in the repr of a t-string, with default formatting rules we soon have text crumpled to the right of the screen... but I believe it is still more readable than

Template(strings=('<div>', '</div>'), interpolations=(Interpolation(Template(strings=('<span ', ' da
ta-value=', '>', '</span>'), interpolations=(Interpolation({'id': 'main'}, 'attributes', None, ''),  
Interpolation('shrubbery', 'attribute_value', None, ''), Interpolation('hello', 'content', None, '')
)), 'template', None, ''),))

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-134551: Add t-strings support to pprint #134577

Activity

1. loic-simon

   added

   type-featureA feature request or enhancementA feature request or enhancement

   on May 22, 2025
2. emmatyping

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on May 23, 2025
3. hugovk commented on May 23, 2025

   

   hugovk

   on May 23, 2025

   Member

   More actions

   Good idea, cc @davepeck @lysnikolaou

   ---

   More complex examples (inspired from the PEP), to give a sense of what it could look like:

   >>> attributes = {"id": "main"}
   >>> attribute_value = "shrubbery"
   >>> content = "hello"
   >>> template = t"<span {attributes} data-value={attribute_value}>{content}</span>"
   >>> pp(template)
   Template(strings=('<span ', ' data-value=', '>', '</span>'),
            interpolations=(Interpolation({'id': 'main'}, 'attributes', None, ''),
                            Interpolation('shrubbery',
                                          'attribute_value',
                                          None,
                                          ''),
                            Interpolation('hello', 'content', None, '')))
   >>>
   >>> nested = t"<div>{template}</div>"
   >>> pp(nested)
   Template(strings=('<div>', '</div>'),
            interpolations=(Interpolation(Template(strings=('<span ',
                                                            ' data-value=',
                                                            '>',
                                                            '</span>'),
                                                   interpolations=(Interpolation({'id': 'main'},
                                                                                 'attributes',
                                                                                 None,
                                                                                 ''),
                                                                   Interpolation('shrubbery',
                                                                                 'attribute_value',
                                                                                 None,
                                                                                 ''),
                                                                   Interpolation('hello',
                                                                                 'content',
                                                                                 None,
                                                                                 ''))),
                                          'template',
                                          None,
                                          ''),))

   Or something like Black formatting takes up less vertical and horizontal space:

   Template(
       strings=("<div>", "</div>"),
       interpolations=(
           Interpolation(
               Template(
                   strings=("<span ", " data-value=", ">", "</span>"),
                   interpolations=(
                       Interpolation({"id": "main"}, "attributes", None, ""),
                       Interpolation("shrubbery", "attribute_value", None, ""),
                       Interpolation("hello", "content", None, ""),
                   ),
               ),
               "template",
               None,
               "",
           ),
       ),
   )

   And taking the simpler case:

   >>> from pprint import pp
   >>> name = "World"
   >>> pp(t"Hello {World}")
   Template(strings=('Hello ', ''),
            interpolations=(Interpolation('World', 'name', None, ''),))""")

   Formats like:

   Template(
       strings=("Hello ", ""), interpolations=(Interpolation("World", "name", None, ""))
   )

   Or with --line-length 79 uses more vertical space but feels more readable:

   Template(
       strings=("Hello ", ""),
       interpolations=(Interpolation("World", "name", None, ""),),
   )

   Obviously we don't need to implement the full flexibility and complexity of Black-style formatting, but perhaps something along these lines?
4. loic-simon commented on May 23, 2025

   

   loic-simon

   on May 23, 2025

   ContributorAuthor

   More actions

   Or something like Black formatting takes up less vertical and horizontal space:

   I didn't dare to get away from pprint conventions (that follow PEP8, if I'm not mistaken) 😄 but I agree it would be way more readeable!
5. lysnikolaou commented on Jun 3, 2025

   

   lysnikolaou

   on Jun 3, 2025

   Member

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   I agree with @hugovk that Black-like formatting makes this more readable. If people are okay with that, I'd certainly prefer it.

   Reacted by Hugo van Kemenade
6. hugovk

   added a commit that references this issue on Apr 14, 2026

   gh-134551: Add t-strings support to pprint (#134577)

   74a4f8c
7. hugovk

   closed this as completedon Apr 14, 2026
8. ljfp

   added a commit that references this issue on Apr 25, 2026

   pythongh-134551: Add t-strings support to pprint (python#134577)

   e3bf7d2

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