Unravelling Python's syntactic sugar source code.

There are accompanying blog posts to go with all of the code in this repository.

1. obj.attr ➠ builtins.getattr(obj, "attr") (including object.__getattribute__())
2. a + b ➠ operator.__add__(a, b)
3. a - b ➠ operator.__sub__(a, b)
4. a * b ➠ operator.__mul__(a, b)
5. a @ b ➠ operator.__matmul__(a, b)
6. a / b ➠ operator.__truediv__(a, b)
7. a // b ➠ operator.__floordiv__(a, b)
8. a % b ➠ operator.__mod__(a, b)
9. a ** b ➠ operator.__pow__(a, b)
10. a << b ➠ operator.__lshift__(a, b)
11. a >> b ➠ operator.__rshift__(a, b)
12. a & b ➠ operator.__and__(a, b)
13. a ^ b ➠ operator.__xor__(a, b)
14. a | b ➠ operator.__or__(a, b)
15. a += b ➠ a = operator.__iadd__(a, b)
16. a -= b ➠ a = operator.__isub__(a, b)
17. a *= b ➠ a = operator.__imul__(a, b)
18. a @= b ➠ a = operator.__imatmul__(a, b)
19. a /= b ➠ a = operator.__itruediv__(a, b)
20. a //= b ➠ a = operator.__ifloordiv__(a, b)
21. a %= b ➠ a = operator.__imod__(a, b)
22. a **= b ➠ a = operator.__ipow__(a, b)
23. a <<= b ➠ a = operator.__ilshift__(a, b)
24. a >>= b ➠ a = operator.__irshift__(a, b)
25. a &= b ➠ a = operator.__iand__(a, b)
26. a ^= b ➠ a = operator.__ixor__(a, b)
27. a |= b ➠ a = operator.__ior__(a, b)
28. ~ a ➠ operator.__invert__(a)
29. - a ➠ operator.__neg__(a)
30. + a ➠ operator.__pos__(a)
31. a == b ➠ operator.__eq__(a, b) (including object.__eq__())
32. a != b ➠ operator.__ne__(a, b) (including object.__ne__())
33. a < b ➠ operator.__lt__(a, b)
34. a <= b ➠ operator.__le__(a, b)
35. a > b ➠ operator.__gt__(a, b)
36. a >= b ➠ operator.__ge__(a, b)
37. a is b ➠ operator.is_(a, b)
38. a is not b ➠ operator.is_not(a, b)
39. not a ➠ operator.not_(a)
40. a in b ➠ operator.__contains__(b, a)
41. a not in b ➠ operator.not_(operator.__contains__(b, a))
42. a or b ➠ _temp if (_temp := a) else b
43. a and b ➠ _temp if not (_temp := a) else b
44. import a.b ➠ a = __import__('a.b', globals(), locals())
45. import a.b as c ➠ c = __import__('a', globals(), locals(), ['b'], 0).b
46. from .a import b ➠ b = __import__('a', globals(), locals(), ['b'], 1).b
47. from .a import b as c ➠ c = __import__('a', globals(), locals(), ['b'], 1).b
48. assert ... ➠ see below
49. for ... ➠ see below (including builtins.iter() and builtins.next())
50. pass ➠ "pass"
51. with ... ➠ see below
52. async def ... ➠ see below
53. await ... ➠ desugar.builtins._await(...)

assert a, b

➠

if __debug__:
    if not a:
        raise AssertionError(b)

assert a

➠

if __debug__:
    if not a:
        raise AssertionError

for a in b:
    c

➠

_iter = iter(b)
while True:
    try:
        a = next(_iter)
    except StopIteration:
        break
    else:
        c
del _iter

for a in b:
    c
else:
    d

➠

_iter = iter(b)
_looping = True
while _looping:
    try:
        a = next(_iter)
    except StopIteration:
        _looping = False
        continue
    else:
        c
else:
    d
del _iter, _looping

with a as b:
    c

➠

_enter = type(a).__enter__
_exit = type(a).__exit__
b = _enter(a)

try:
    c
except:
    if not _exit(a, *sys.exc_info()):
        raise
else:
    _exit(a, None, None, None)

async def spam():
    ...

➠

@types.coroutine
def spam():
    ...

Taken from the keyword module.

1. yield
2. lambda

1. break

2. continue

3. if/elif/else

4. while/else

5. async for/else *

6. async with *

7. def

8. class ~

9. try/except/else/finally

10. global

11. nonlocal

12. del

13. raise/from

14. return

Taken from the token module.

1. =

2. :=

3. [] for list display *

4. [] for list comprehensions *

5. [] for subscriptions (get, set, del), : for slicing *

6. {} for set display *

7. {} for set comprehensions *

8. {} for dictionary display *

9. {} for dictionary comprehensions *

10. () for tuple display *

11. () for calls

12. @ for decorators *

13. ,

14. ; *

15. ... *

The list below ignores literals which are represented via syntax above. For instance, lists are ignored as they are represented by [] tokens.

1. None
2. False
3. True
4. Bytes (b, r)
5. Strings (u, f, r; single line, multi-line)
6. Integers (base-10, b, o, x)
7. Floats (point, e)
8. Complex/imaginary numbers