Python’s new t-strings

> In addition, I hope that the tooling ecosystem will adapt to support t-strings. For instance, I’d love to see black and ruff format t-string contents, and vscode color those contents, if they’re a common type like HTML or SQL.

This is such a strange take on t-strings. The only way for anything to infer that the template string is supposed to turn into valid HTML or SQL is to base it of the apparent syntax in the string, which can only be done in an ad-hoc fashion and has nothing to do with the template string feature.

The way the feature has been designed there is no indication in the string itself what type of content it is or what it will eventually be converted to. It’s all handled by the converting function.

As others have added, something like sql”select * from {table}” would have been able to do this, but there’s not even any guarantees that something that is in a template that will be converted into valid sql by a converting function should be any type of valid sql prior to that conversion. For all you know t“give me {table} but only {columns}” might be a converted into valid sql after the template is processed.

Couldn’t you do this with a type annotation? e.g. SQLAlchemy could have a SQL type so tools like mypy could see a Template instance and confirm you’re using it safely but Black, Ruff, or SQLFluff could look for the more specialized Annotated[Template, SQL] to realize that the template could be formatted as SQL, and something like Django could even have Annotated[Template, Email], Annotated[Template, HTML], or Annotated[Template, JSX] to indicate what context the same templating syntax is targeting.

This is what we discussed in the first revision of the PEP (the use of `Annotated`.) But we found out: linters don't know anything about the Python type system.

We hope to get a community around all of this, stuff at PyCon US, EuroPython, etc. and work some of this out. The JSX/TSX world really has good tooling. We can provide that for those that want it, perhaps better on some aspects.