pyupgrade
A tool (and pre-commit hook) to automatically upgrade syntax for newer versions of the language.
Installation
As a pre-commit hook
See pre-commit for instructions
Sample .pre-commit-config.yaml:
- repo: https://github.com/asottile/pyupgrade rev: v3.21.2 hooks: - id: pyupgrade
Implemented features
Set literals
-set(()) +set() -set([]) +set() -set((1,)) +{1} -set((1, 2)) +{1, 2} -set([1, 2]) +{1, 2} -set(x for x in y) +{x for x in y} -set([x for x in y]) +{x for x in y}
Dictionary comprehensions
-dict((a, b) for a, b in y) +{a: b for a, b in y} -dict([(a, b) for a, b in y]) +{a: b for a, b in y}
Replace unnecessary lambdas in collections.defaultdict calls
-defaultdict(lambda: []) +defaultdict(list) -defaultdict(lambda: list()) +defaultdict(list) -defaultdict(lambda: {}) +defaultdict(dict) -defaultdict(lambda: dict()) +defaultdict(dict) -defaultdict(lambda: ()) +defaultdict(tuple) -defaultdict(lambda: tuple()) +defaultdict(tuple) -defaultdict(lambda: set()) +defaultdict(set) -defaultdict(lambda: 0) +defaultdict(int) -defaultdict(lambda: 0.0) +defaultdict(float) -defaultdict(lambda: 0j) +defaultdict(complex) -defaultdict(lambda: '') +defaultdict(str)
Format Specifiers
-'{0} {1}'.format(1, 2) +'{} {}'.format(1, 2) -'{0}' '{1}'.format(1, 2) +'{}' '{}'.format(1, 2)
printf-style string formatting
Availability:
- Unless
--keep-percent-formatis passed.
-'%s %s' % (a, b) +'{} {}'.format(a, b) -'%r %2f' % (a, b) +'{!r} {:2f}'.format(a, b) -'%(a)s %(b)s' % {'a': 1, 'b': 2} +'{a} {b}'.format(a=1, b=2)
Unicode literals
-u'foo' +'foo' -u"foo" +'foo' -u'''foo''' +'''foo'''
Invalid escape sequences
# strings with only invalid sequences become raw strings -'\d' +r'\d' # strings with mixed valid / invalid sequences get escaped -'\n\d' +'\n\\d' -u'\d' +r'\d' # this fixes a syntax error in python3.3+ -'\N' +r'\N'
is / is not comparison to constant literals
In python3.8+, comparison to literals becomes a SyntaxWarning as the success
of those comparisons is implementation specific (due to common object caching).
-x is 5 +x == 5 -x is not 5 +x != 5 -x is 'foo' +x == 'foo'
.encode() to bytes literals
-'foo'.encode() +b'foo' -'foo'.encode('ascii') +b'foo' -'foo'.encode('utf-8') +b'foo' -u'foo'.encode() +b'foo' -'\xa0'.encode('latin1') +b'\xa0'
extraneous parens in print(...)
A fix for python-modernize/python-modernize#178
# ok: printing an empty tuple print(()) # ok: printing a tuple print((1,)) # ok: parenthesized generator argument sum((i for i in range(3)), []) # fixed: -print(("foo")) +print("foo")
constant fold isinstance / issubclass / except
-isinstance(x, (int, int)) +isinstance(x, int) -issubclass(y, (str, str)) +issubclass(y, str) try: raises() -except (Error1, Error1, Error2): +except (Error1, Error2): pass
unittest deprecated aliases
Rewrites deprecated unittest method aliases to their non-deprecated forms.
from unittest import TestCase
class MyTests(TestCase):
def test_something(self):
- self.failUnlessEqual(1, 1)
+ self.assertEqual(1, 1)
- self.assertEquals(1, 1)
+ self.assertEqual(1, 1)super() calls
class C(Base):
def f(self):
- super(C, self).f()
+ super().f()"new style" classes
rewrites class declaration
-class C(object): pass +class C: pass -class C(B, object): pass +class C(B): pass
removes __metaclass__ = type declaration
class C:
- __metaclass__ = typeforced str("native") literals
-str() +'' -str("foo") +"foo"
.encode("utf-8")
-"foo".encode("utf-8") +"foo".encode()
# coding: ... comment
as of PEP 3120, the default encoding for python source is UTF-8
__future__ import removal
Availability:
- by default removes
nested_scopes,generators,with_statement,absolute_import,division,print_function,unicode_literals --py37-pluswill also removegenerator_stop
-from __future__ import with_statementRemove unnecessary py3-compat imports
-from io import open -from six.moves import map -from builtins import object # python-future
import replacements
Availability:
--py36-plus(and others) will replace imports
see also reorder-python-imports
some examples:
-from collections import deque, Mapping +from collections import deque +from collections.abc import Mapping
-from typing import Sequence +from collections.abc import Sequence
-from typing_extensions import Concatenate +from typing import Concatenate
rewrite mock imports
Availability:
-from mock import patch +from unittest.mock import patch
yield => yield from
def f(): - for x in y: - yield x + yield from y - for a, b in c: - yield (a, b) + yield from c
Python2 and old Python3.x blocks
import sys -if sys.version_info < (3,): # also understands `six.PY2` (and `not`), `six.PY3` (and `not`) - print('py2') -else: - print('py3') +print('py3')
Availability:
--py36-pluswill remove Python <= 3.5 only blocks--py37-pluswill remove Python <= 3.6 only blocks- so on and so forth
# using --py36-plus for this example import sys -if sys.version_info < (3, 6): - print('py3.5') -else: - print('py3.6+') +print('py3.6+') -if sys.version_info <= (3, 5): - print('py3.5') -else: - print('py3.6+') +print('py3.6+') -if sys.version_info >= (3, 6): - print('py3.6+') -else: - print('py3.5') +print('py3.6+')
Note that if blocks without an else will not be rewritten as it could introduce a syntax error.
remove six compatibility code
-six.text_type +str -six.binary_type +bytes -six.class_types +(type,) -six.string_types +(str,) -six.integer_types +(int,) -six.unichr +chr -six.iterbytes +iter -six.print_(...) +print(...) -six.exec_(c, g, l) +exec(c, g, l) -six.advance_iterator(it) +next(it) -six.next(it) +next(it) -six.callable(x) +callable(x) -six.moves.range(x) +range(x) -six.moves.xrange(x) +range(x) -from six import text_type -text_type +str -@six.python_2_unicode_compatible class C: def __str__(self): return u'C()' -class C(six.Iterator): pass +class C: pass -class C(six.with_metaclass(M, B)): pass +class C(B, metaclass=M): pass -@six.add_metaclass(M) -class C(B): pass +class C(B, metaclass=M): pass -isinstance(..., six.class_types) +isinstance(..., type) -issubclass(..., six.integer_types) +issubclass(..., int) -isinstance(..., six.string_types) +isinstance(..., str) -six.b('...') +b'...' -six.u('...') +'...' -six.byte2int(bs) +bs[0] -six.indexbytes(bs, i) +bs[i] -six.int2byte(i) +bytes((i,)) -six.iteritems(dct) +dct.items() -six.iterkeys(dct) +dct.keys() -six.itervalues(dct) +dct.values() -next(six.iteritems(dct)) +next(iter(dct.items())) -next(six.iterkeys(dct)) +next(iter(dct.keys())) -next(six.itervalues(dct)) +next(iter(dct.values())) -six.viewitems(dct) +dct.items() -six.viewkeys(dct) +dct.keys() -six.viewvalues(dct) +dct.values() -six.create_unbound_method(fn, cls) +fn -six.get_unbound_function(meth) +meth -six.get_method_function(meth) +meth.__func__ -six.get_method_self(meth) +meth.__self__ -six.get_function_closure(fn) +fn.__closure__ -six.get_function_code(fn) +fn.__code__ -six.get_function_defaults(fn) +fn.__defaults__ -six.get_function_globals(fn) +fn.__globals__ -six.raise_from(exc, exc_from) +raise exc from exc_from -six.reraise(tp, exc, tb) +raise exc.with_traceback(tb) -six.reraise(*sys.exc_info()) +raise -six.assertCountEqual(self, a1, a2) +self.assertCountEqual(a1, a2) -six.assertRaisesRegex(self, e, r, fn) +self.assertRaisesRegex(e, r, fn) -six.assertRegex(self, s, r) +self.assertRegex(s, r) # note: only for *literals* -six.ensure_binary('...') +b'...' -six.ensure_str('...') +'...' -six.ensure_text('...') +'...'
open alias
-with io.open('f.txt') as f: +with open('f.txt') as f: ...
redundant open modes
-open("foo", "U") +open("foo") -open("foo", "Ur") +open("foo") -open("foo", "Ub") +open("foo", "rb") -open("foo", "rUb") +open("foo", "rb") -open("foo", "r") +open("foo") -open("foo", "rt") +open("foo") -open("f", "r", encoding="UTF-8") +open("f", encoding="UTF-8") -open("f", "wt") +open("f", "w")
OSError aliases
# also understands: # - IOError # - WindowsError # - mmap.error and uses of `from mmap import error` # - select.error and uses of `from select import error` # - socket.error and uses of `from socket import error` def throw(): - raise EnvironmentError('boom') + raise OSError('boom') def catch(): try: throw() - except EnvironmentError: + except OSError: handle_error()
TimeoutError aliases
Availability:
--py310-plusforsocket.timeout--py311-plusforasyncio.TimeoutError
def throw(a):
if a:
- raise asyncio.TimeoutError('boom')
+ raise TimeoutError('boom')
else:
- raise socket.timeout('boom')
+ raise TimeoutError('boom')
def catch(a):
try:
throw(a)
- except (asyncio.TimeoutError, socket.timeout):
+ except TimeoutError:
handle_error()typing.Text str alias
-def f(x: Text) -> None: +def f(x: str) -> None: ...
Unpacking list comprehensions
-foo, bar, baz = [fn(x) for x in items] +foo, bar, baz = (fn(x) for x in items)
Rewrite xml.etree.cElementTree to xml.etree.ElementTree
-import xml.etree.cElementTree as ET +import xml.etree.ElementTree as ET -from xml.etree.cElementTree import XML +from xml.etree.ElementTree import XML
Rewrite type of primitive
-type('') +str -type(b'') +bytes -type(0) +int -type(0.) +float
typing.NamedTuple / typing.TypedDict py36+ syntax
Availability:
--py36-plusis passed on the commandline.
-NT = typing.NamedTuple('NT', [('a', int), ('b', Tuple[str, ...])]) +class NT(typing.NamedTuple): + a: int + b: Tuple[str, ...] -D1 = typing.TypedDict('D1', a=int, b=str) +class D1(typing.TypedDict): + a: int + b: str -D2 = typing.TypedDict('D2', {'a': int, 'b': str}) +class D2(typing.TypedDict): + a: int + b: str
f-strings
Availability:
--py36-plusis passed on the commandline.
-'{foo} {bar}'.format(foo=foo, bar=bar) +f'{foo} {bar}' -'{} {}'.format(foo, bar) +f'{foo} {bar}' -'{} {}'.format(foo.bar, baz.womp) +f'{foo.bar} {baz.womp}' -'{} {}'.format(f(), g()) +f'{f()} {g()}' -'{x}'.format(**locals()) +f'{x}'
note: pyupgrade is intentionally timid and will not create an f-string
if it would make the expression longer or if the substitution parameters are
sufficiently complicated (as this can decrease readability).
subprocess.run: replace universal_newlines with text
Availability:
--py37-plusis passed on the commandline.
-output = subprocess.run(['foo'], universal_newlines=True) +output = subprocess.run(['foo'], text=True)
subprocess.run: replace stdout=subprocess.PIPE, stderr=subprocess.PIPE with capture_output=True
Availability:
--py37-plusis passed on the commandline.
-output = subprocess.run(['foo'], stdout=subprocess.PIPE, stderr=subprocess.PIPE) +output = subprocess.run(['foo'], capture_output=True)
remove parentheses from @functools.lru_cache()
Availability:
--py38-plusis passed on the commandline.
import functools -@functools.lru_cache() +@functools.lru_cache def expensive(): ...
shlex.join
Availability:
--py38-plusis passed on the commandline.
-' '.join(shlex.quote(arg) for arg in cmd) +shlex.join(cmd)
replace @functools.lru_cache(maxsize=None) with shorthand
Availability:
--py39-plusis passed on the commandline.
import functools -@functools.lru_cache(maxsize=None) +@functools.cache def expensive(): ...
pep 585 typing rewrites
Availability:
- File imports
from __future__ import annotations- Unless
--keep-runtime-typingis passed on the commandline.
- Unless
--py39-plusis passed on the commandline.
-def f(x: List[str]) -> None: +def f(x: list[str]) -> None: ...
pep 604 typing rewrites
Availability:
- File imports
from __future__ import annotations- Unless
--keep-runtime-typingis passed on the commandline.
- Unless
--py310-plusis passed on the commandline.
-def f() -> Optional[str]: +def f() -> str | None: ...
-def f() -> Union[int, str]: +def f() -> int | str: ...
pep 696 TypeVar defaults
Availability:
- File imports
from __future__ import annotations- Unless
--keep-runtime-typingis passed on the commandline.
- Unless
--py313-plusis passed on the commandline.
-def f() -> Generator[int, None, None]: +def f() -> Generator[int]: yield 1
-async def f() -> AsyncGenerator[int, None]: +async def f() -> AsyncGenerator[int]: yield 1
remove quoted annotations
Availability:
- File imports
from __future__ import annotations
-def f(x: 'queue.Queue[int]') -> C: +def f(x: queue.Queue[int]) -> C:
use datetime.UTC alias
Availability:
--py311-plusis passed on the commandline.
import datetime -datetime.timezone.utc +datetime.UTC