bpo-39702: Relax grammar restrictions on decorators (PEP 614) (GH-18570)
diff --git a/Lib/test/test_decorators.py b/Lib/test/test_decorators.py
index 8953f64..298979e 100644
--- a/Lib/test/test_decorators.py
+++ b/Lib/test/test_decorators.py
@@ -151,21 +151,18 @@
self.assertEqual(counts['double'], 4)
def test_errors(self):
- # Test syntax restrictions - these are all compile-time errors:
- #
- for expr in [ "1+2", "x[3]", "(1, 2)" ]:
- # Sanity check: is expr is a valid expression by itself?
- compile(expr, "testexpr", "exec")
- codestr = "@%s\ndef f(): pass" % expr
- self.assertRaises(SyntaxError, compile, codestr, "test", "exec")
+ # Test SyntaxErrors:
+ for stmt in ("x,", "x, y", "x = y", "pass", "import sys"):
+ compile(stmt, "test", "exec") # Sanity check.
+ with self.assertRaises(SyntaxError):
+ compile(f"@{stmt}\ndef f(): pass", "test", "exec")
- # You can't put multiple decorators on a single line:
- #
- self.assertRaises(SyntaxError, compile,
- "@f1 @f2\ndef f(): pass", "test", "exec")
-
- # Test runtime errors
+ # Test TypeErrors that used to be SyntaxErrors:
+ for expr in ("1.+2j", "[1, 2][-1]", "(1, 2)", "True", "...", "None"):
+ compile(expr, "test", "eval") # Sanity check.
+ with self.assertRaises(TypeError):
+ exec(f"@{expr}\ndef f(): pass")
def unimp(func):
raise NotImplementedError
@@ -179,6 +176,13 @@
code = compile(codestr, "test", "exec")
self.assertRaises(exc, eval, code, context)
+ def test_expressions(self):
+ for expr in (
+ "(x,)", "(x, y)", "x := y", "(x := y)", "x @y", "(x @ y)", "x[0]",
+ "w[x].y.z", "w + x - (y + z)", "x(y)()(z)", "[w, x, y][z]", "x.y",
+ ):
+ compile(f"@{expr}\ndef f(): pass", "test", "exec")
+
def test_double(self):
class C(object):
@funcattrs(abc=1, xyz="haha")
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index 2ed73e3..922a516 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -460,7 +460,7 @@
def test_funcdef(self):
### [decorators] 'def' NAME parameters ['->' test] ':' suite
- ### decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
+ ### decorator: '@' namedexpr_test NEWLINE
### decorators: decorator+
### parameters: '(' [typedargslist] ')'
### typedargslist: ((tfpdef ['=' test] ',')*
@@ -666,6 +666,20 @@
def f(x) -> list: pass
self.assertEqual(f.__annotations__, {'return': list})
+ # Test expressions as decorators (PEP 614):
+ @False or null
+ def f(x): pass
+ @d := null
+ def f(x): pass
+ @lambda f: null(f)
+ def f(x): pass
+ @[..., null, ...][1]
+ def f(x): pass
+ @null(null)(null)
+ def f(x): pass
+ @[null][0].__call__.__call__
+ def f(x): pass
+
# test closures with a variety of opargs
closure = 1
def f(): return closure
@@ -1515,13 +1529,27 @@
def meth2(self, arg): pass
def meth3(self, a1, a2): pass
- # decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
+ # decorator: '@' namedexpr_test NEWLINE
# decorators: decorator+
# decorated: decorators (classdef | funcdef)
def class_decorator(x): return x
@class_decorator
class G: pass
+ # Test expressions as decorators (PEP 614):
+ @False or class_decorator
+ class H: pass
+ @d := class_decorator
+ class I: pass
+ @lambda c: class_decorator(c)
+ class J: pass
+ @[..., class_decorator, ...][1]
+ class K: pass
+ @class_decorator(class_decorator)(class_decorator)
+ class L: pass
+ @[class_decorator][0].__call__.__call__
+ class M: pass
+
def test_dictcomps(self):
# dictorsetmaker: ( (test ':' test (comp_for |
# (',' test ':' test)* [','])) |
diff --git a/Lib/test/test_parser.py b/Lib/test/test_parser.py
index 7295f66..73178f3 100644
--- a/Lib/test/test_parser.py
+++ b/Lib/test/test_parser.py
@@ -226,6 +226,27 @@
self.check_suite("@funcattrs()\n"
"def f(): pass")
+ self.check_suite("@False or x\n"
+ "def f(): pass")
+ self.check_suite("@d := x\n"
+ "def f(): pass")
+ self.check_suite("@lambda f: x(f)\n"
+ "def f(): pass")
+ self.check_suite("@[..., x, ...][1]\n"
+ "def f(): pass")
+ self.check_suite("@x(x)(x)\n"
+ "def f(): pass")
+ self.check_suite("@(x, x)\n"
+ "def f(): pass")
+ self.check_suite("@...\n"
+ "def f(): pass")
+ self.check_suite("@None\n"
+ "def f(): pass")
+ self.check_suite("@w @(x @y) @(z)\n"
+ "def f(): pass")
+ self.check_suite("@w[x].y.z\n"
+ "def f(): pass")
+
# keyword-only arguments
self.check_suite("def f(*, a): pass")
self.check_suite("def f(*, a = 5): pass")
@@ -270,6 +291,27 @@
"@decorator2\n"
"class foo():pass")
+ self.check_suite("@False or x\n"
+ "class C: pass")
+ self.check_suite("@d := x\n"
+ "class C: pass")
+ self.check_suite("@lambda f: x(f)\n"
+ "class C: pass")
+ self.check_suite("@[..., x, ...][1]\n"
+ "class C: pass")
+ self.check_suite("@x(x)(x)\n"
+ "class C: pass")
+ self.check_suite("@(x, x)\n"
+ "class C: pass")
+ self.check_suite("@...\n"
+ "class C: pass")
+ self.check_suite("@None\n"
+ "class C: pass")
+ self.check_suite("@w @(x @y) @(z)\n"
+ "class C: pass")
+ self.check_suite("@w[x].y.z\n"
+ "class C: pass")
+
def test_import_from_statement(self):
self.check_suite("from sys.path import *")
self.check_suite("from sys.path import dirname")