Python 3.14+Strings (str)construct

t-strings

formatting

t'...' looks like an f-string but produces a Template object, not a str: the text parts and interpolated values are kept apart (Python 3.14+).

Syntax

t'текст {выражение}'
T"текст {выражение!r:формат}"

The main trap: a t-string is not a str. It is never equal to a string with the same text (the comparison gives False) and cannot be joined to a str with + (TypeError), and str(tpl) gives the template's repr, not the finished text. Your code builds the string: it iterates over the template, getting text pieces and Interpolation objects, and can, for example, escape values for HTML or SQL. If you just need a string, use an f-string.

Examples

# Python 3.14+
name = 'Bob'
tpl = t'Hi {name}!'
print(type(tpl).__name__)  # → Template
print(tpl.strings, tpl.values)  # → ('Hi ', '!') ('Bob',)
print(tpl == 'Hi Bob!')  # → False
print(str(tpl)[:9])  # → Template( — repr шаблона, а не текст
tpl + '?'  # → TypeError

# Python 3.14+
from string.templatelib import Interpolation
name = '<b>'
tpl = t'Hi {name}!'
parts = []
for part in tpl:
    if isinstance(part, Interpolation):
        part = str(part.value).replace('<', '&lt;').replace('>', '&gt;')
    parts.append(part)
print(''.join(parts))  # → Hi &lt;b&gt;!

See also

Common errors

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