Use f-strings instead of str.format within importlib

[gpshead]

BPO	38693
Nosy	@gpshead, @jaraco, @ericvsmith, @serhiy-storchaka, @csabella, @miss-islington, @tirkarthi, @FFY00
PRs	bpo-38693: Use f-strings instead of str.format() within importlib #17058 bpo-38693: importlib.metadata f-strings #26383 [3.10] bpo-38693: importlib.metadata f-strings (GH-26383) #26386 bpo-38693: Prefer f-strings in importlib.resources (importlib_resources 5.0.6). #26387 [3.10] bpo-38693: Prefer f-strings in importlib.resources (importlib_resources 5.0.6). (GH-26387) #26389

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/gpshead'
closed_at = None
created_at = <Date 2019-11-05.06:20:17.309>
labels = ['3.11', 'performance']
title = 'Use f-strings instead of str.format within importlib'
updated_at = <Date 2021-05-26.21:09:35.360>
user = 'https://github.com/gpshead'

bugs.python.org fields:

activity = <Date 2021-05-26.21:09:35.360>
actor = 'jaraco'
assignee = 'gregory.p.smith'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2019-11-05.06:20:17.309>
creator = 'gregory.p.smith'
dependencies = []
files = []
hgrepos = []
issue_num = 38693
keywords = ['patch']
message_count = 9.0
messages = ['356005', '369672', '378998', '393617', '393629', '394453', '394454', '394460', '394463']
nosy_count = 8.0
nosy_names = ['gregory.p.smith', 'jaraco', 'eric.smith', 'serhiy.storchaka', 'cheryl.sabella', 'miss-islington', 'xtreak', 'FFY00']
pr_nums = ['17058', '26383', '26386', '26387', '26389']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue38693'
versions = ['Python 3.11']

[gpshead]

importlib is full of str.format calls, modernizing it to use f-strings is a slight performance win and much more readable.

[csabella]

Did you want this one to land in 3.9?

[gpshead]

Status: Waiting until after the importlib.metadata and importlib.resources backports drop support for both Python 2.7 and 3.5 as keeping them in sync would be a pain for maintainers (per jaraco on our sprint importlib-any chat today)

[FFY00]

Both importlib_metadata and importlib_resources have dropped support for Python 2.7 and 3.5, this should now be unblocked.

[serhiy-storchaka]

I just have merged a change which makes many C-style formatting as fast as f-strings (bpo-28307) and am working on supporting more format codes (%d, %x, %f, etc). Using C-style formatting can be a good option if you want performance and backward compatibility. It was faster than str.format() even without that optimization.

[miss-islington]

New changeset e6c815d by Jason R. Coombs in branch 'main':
bpo-38693: importlib.metadata f-strings (GH-26383)
e6c815d

[miss-islington]

New changeset 78a8428 by Miss Islington (bot) in branch '3.10':
bpo-38693: importlib.metadata f-strings (GH-26383)
78a8428

[miss-islington]

New changeset f6fbdb9 by Jason R. Coombs in branch 'main':
bpo-38693: Prefer f-strings in importlib.resources (importlib_resources 5.0.6). (GH-26387)
f6fbdb9

[jaraco]

New changeset 97b4576 by Miss Islington (bot) in branch '3.10':
bpo-38693: Prefer f-strings in importlib.resources (importlib_resources 5.0.6). (GH-26387) (bpo-26389)
97b4576

[gpshead]

#17058 did this for Lib/importlib/_bootstrap.py

[gpshead]

remaining things to consider (not all need to be converted):

$ grep -R '[.]format' Lib/importlib/
Lib/importlib/_bootstrap_external.py:    path_tmp = '{}.{}'.format(path, id(path))
Lib/importlib/_bootstrap_external.py:            raise ValueError('{!r} is not alphanumeric'.format(optimization))
Lib/importlib/_bootstrap_external.py:        almost_filename = '{}.{}{}'.format(almost_filename, _OPT, optimization)
Lib/importlib/_bootstrap_external.py:        _warnings.warn(msg.format(portions[0]), ImportWarning)
Lib/importlib/_bootstrap_external.py:        raise ImportError('Non-code object in {!r}'.format(bytecode_path),
Lib/importlib/_bootstrap_external.py:        key = registry_key.format(fullname=fullname,
Lib/importlib/_bootstrap_external.py:                              'returns None'.format(module.__name__))
Lib/importlib/_bootstrap_external.py:        return '_NamespacePath({!r})'.format(self._path)
Lib/importlib/_bootstrap_external.py:                    new_name = '{}.{}'.format(name, suffix.lower())
Lib/importlib/_bootstrap_external.py:        return 'FileFinder({!r})'.format(self.path)
Lib/importlib/metadata/__init__.py:        return text and map('"{}"'.format, text.splitlines())
Lib/importlib/resources/_adapters.py:        "Invalid mode value '{}', only 'r' and 'rb' are supported".format(mode)
Lib/importlib/_bootstrap.py:        print(message.format(*args), file=sys.stderr)
Lib/importlib/__init__.py:            raise ValueError('{}.__loader__ is None'.format(name))
Lib/importlib/__init__.py:        raise ValueError('{}.__loader__ is not set'.format(name)) from None
Lib/importlib/__init__.py:            raise ImportError('spec for {} missing loader'.format(name),
Lib/importlib/__init__.py:            raise TypeError(msg.format(name))
Lib/importlib/__init__.py:        raise ImportError(msg.format(name), name=name)
Lib/importlib/__init__.py:                raise ImportError(msg.format(parent_name),
Lib/importlib/util.py:            raise ValueError('{}.__spec__ is not set'.format(name)) from None
Lib/importlib/util.py:                raise ValueError('{}.__spec__ is None'.format(name))
Lib/importlib/util.py:            raise ValueError('{}.__spec__ is not set'.format(name)) from None
Lib/importlib/util.py:                raise ValueError('{}.__spec__ is None'.format(name))