FilesExpand file tree

 master

/

cache.py

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

77 lines (59 loc) · 2.43 KB

 master

/

cache.py

Copy path

Top

File metadata and controls

• Code
• Blame

77 lines (59 loc) · 2.43 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

"""

- the popular ``_memoize_default`` works like a typical memoize and returns the

default otherwise.

- ``CachedMetaClass`` uses ``_memoize_default`` to do the same with classes.

"""

_NO_DEFAULT = object()

def _memoize_default(default=_NO_DEFAULT, evaluator_is_first_arg=False, second_arg_is_evaluator=False):

""" This is a typical memoization decorator, BUT there is one difference:

To prevent recursion it sets defaults.

Preventing recursion is in this case the much bigger use than speed. I

don't think, that there is a big speed difference, but there are many cases

where recursion could happen (think about a = b; b = a).

"""

def func(function):

def wrapper(obj, *args, **kwargs):

# TODO These checks are kind of ugly and slow.

if evaluator_is_first_arg:

cache = obj.memoize_cache

elif second_arg_is_evaluator:

cache = args[0].memoize_cache # needed for meta classes

else:

cache = obj.evaluator.memoize_cache

try:

memo = cache[function]

except KeyError:

memo = {}

cache[function] = memo

key = (obj, args, frozenset(kwargs.items()))

if key in memo:

return memo[key]

else:

if default is not _NO_DEFAULT:

memo[key] = default

rv = function(obj, *args, **kwargs)

memo[key] = rv

return rv

return wrapper

return func

def evaluator_function_cache(default=_NO_DEFAULT):

def decorator(func):

return _memoize_default(default=default, evaluator_is_first_arg=True)(func)

return decorator

def evaluator_method_cache(default=_NO_DEFAULT):

def decorator(func):

return _memoize_default(default=default)(func)

return decorator

def evaluator_as_method_param_cache():

def decorator(call):

return _memoize_default(second_arg_is_evaluator=True)(call)

return decorator

class CachedMetaClass(type):

"""

This is basically almost the same than the decorator above, it just caches

class initializations. Either you do it this way or with decorators, but

with decorators you lose class access (isinstance, etc).

"""

@evaluator_as_method_param_cache()

def __call__(self, *args, **kwargs):

return super(CachedMetaClass, self).__call__(*args, **kwargs)