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Misleading descriptions in the introduce of "Template" #137119
Description
Documentation
The template can then be combined with functions that operate on the template’s structure to produce a str or a string-like result. For example, sanitizing input:
template = t"<p>{evil}</p>" assert html(template) == "<p><script>alert('evil')</script></p>"
As another example, generating HTML attributes from data:
template = t"<img {attributes}>" assert html(template) == '<img src="shrubbery.jpg" alt="looks nice" />'
Compared to using an f-string, the html function has access to template attributes containing the original information: static strings, interpolations, and values from the original scope. Unlike existing templating approaches, t-strings build from the well-known f-string syntax and rules. Template systems thus benefit from Python tooling as they are much closer to the Python language, syntax, scoping, and more.
In PEP-750, the author assumed that you had defined the function html:
For example, imagine we want to generate some HTML. Using template strings, we can define an html() function that allows us to automatically sanitize content:
template = t"<p>{evil}</p>" assert html(template) == "<p><script>alert('evil')</script></p>"
Likewise, our hypothetical html() function can make it easy for developers to add attributes to HTML elements using a dictionary:
template = t"<img {attributes} />" assert html(template) == '<img src="shrubbery.jpg" alt="looks nice" />'
However, in the document, the operation "define" was gone, so that some users will mistakenly think that there is a function html that has been defined.
I think that it is better to explain that the function html should be defined by user, like this:
The template can then be combined with functions that operate on the template’s structure to produce a str or a string-like result. For example, sanitizing input (assuming that you have defined a function
htmlthat can deal with the input to html):
Activity
StanFromIreland commentedon Jul 26, 2025
cc @davepeck @lysnikolaou @pauleveritt
I think the example in the What's New (To be clear: I am not talking about the PEP) would be improved if it featured the implementation. For reference, the current text in the What's New 3.14 is:
davepeck commentedon Jul 29, 2025
Thanks all. I agree that we should probably improve the "What's New" section for 3.14 now that the rest of t-string documentation is starting to take shape. On my "to do" list for the week!
blaisep commentedon Jul 30, 2025
I find this distinction helpful, along with any others that might illustrate the difference from
f-stringsIn fact, I'm thinking that a two column table would be nice. I realize I may be volunteering, but as much as I dislike tables in .rST, I can give it a go.
pauleveritt commentedon Jul 31, 2025
Thanks @blaisep for any help you can give. Feel free to ask me questions. If I don't have the answer, I can find it.
davepeck commentedon Jul 31, 2025
@blaisep @pauleveritt Just saw your comments here. I've got a first pass at this in this PR but still think it needs some work.
StanFromIreland commentedon Nov 24, 2025
It was updated in #139543.