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string.Formatter does not handle non-indexed item and attribute access #129273
Description
Bug report
Bug description:
from argparse import Namespace
fmt = '{[0]} {.a}'
fmt.format([10], Namespace(a=1)) # '10 1'
# ---
import string
string.Formatter().format(fmt, [10], Namespace(a=1))
# KeyError: ''CPython versions tested on:
3.14
Operating systems tested on:
macOS
Activity
dg-pb commentedon Jan 25, 2025
It is arguably a missing feature and not a bug, but I would say it is a bug given this statement in docs:
"The Formatter class in the string module allows you to create and customize your own string formatting behaviors using the same implementation as the built-in format() method."
dg-pb commentedon Jan 25, 2025
Seems like a long-standing issue. Open duplicates:
dg-pb commentedon Jan 26, 2025
#21767 closes all 3 above and this one.
It is ready for core review.
dg-pb commentedon Jan 31, 2025
Fixed by: #21767