This document describes the current stable version of Celery (5.2). For development docs, go here.
celery.utils.functional
¶
Functional-style utilities.
-
class
celery.utils.functional.
LRUCache
(limit=None)[source]¶ LRU Cache implementation using a doubly linked list to track access.
- Parameters
limit (int) – The maximum number of keys to keep in the cache. When a new key is inserted and the limit has been exceeded, the Least Recently Used key will be discarded from the cache.
-
items
() → a set-like object providing a view on D’s items¶
-
iteritems
()¶
-
iterkeys
()¶
-
itervalues
()¶
-
keys
() → a set-like object providing a view on D’s keys¶
-
popitem
() → (k, v), remove and return some (key, value) pair[source]¶ as a 2-tuple; but raise KeyError if D is empty.
-
update
([E, ]**F) → None. Update D from mapping/iterable E and F.[source]¶ If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v
-
values
() → an object providing a view on D’s values¶
-
celery.utils.functional.
chunks
(it, n)[source]¶ Split an iterator into chunks with n elements each.
Warning
it
must be an actual iterator, if you pass this a concrete sequence will get you repeating elements.So
chunks(iter(range(1000)), 10)
is fine, butchunks(range(1000), 10)
is not.Example
# n == 2 >>> x = chunks(iter([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]), 2) >>> list(x) [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10]]
# n == 3 >>> x = chunks(iter([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]), 3) >>> list(x) [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10]]
-
celery.utils.functional.
dictfilter
(d=None, **kw)[source]¶ Remove all keys from dict
d
whose value isNone
.
-
celery.utils.functional.
first
(predicate, it)[source]¶ Return the first element in
it
thatpredicate
accepts.If
predicate
is None it will return the first item that’s notNone
.
-
celery.utils.functional.
firstmethod
(method, on_call=None)[source]¶ Multiple dispatch.
Return a function that with a list of instances, finds the first instance that gives a value for the given method.
The list can also contain lazy instances (
lazy
.)
-
celery.utils.functional.
fun_accepts_kwargs
(fun)[source]¶ Return true if function accepts arbitrary keyword arguments.
-
celery.utils.functional.
head_from_fun
(fun, bound=False, debug=False)[source]¶ Generate signature function from actual function.
-
celery.utils.functional.
is_list
(obj, scalars=(<class 'collections.abc.Mapping'>, <class 'str'>), iters=(<class 'collections.abc.Iterable'>, ))[source]¶ Return true if the object is iterable.
Note
Returns false if object is a mapping or string.
-
class
celery.utils.functional.
lazy
(fun, *args, **kwargs)[source]¶ Holds lazy evaluation.
Evaluated when called or if the
evaluate()
method is called. The function is re-evaluated on every call.- Overloaded operations that will evaluate the promise:
__str__()
,__repr__()
,__cmp__()
.
-
celery.utils.functional.
mattrgetter
(*attrs)[source]¶ Get attributes, ignoring attribute errors.
Like
operator.itemgetter()
but returnNone
on missing attributes instead of raisingAttributeError
.
-
celery.utils.functional.
maybe_evaluate
(value)[source]¶ Evaluate value only if value is a
lazy
instance.
-
celery.utils.functional.
maybe_list
(obj, scalars=(<class 'collections.abc.Mapping'>, <class 'str'>))[source]¶ Return list of one element if
l
is a scalar.
-
celery.utils.functional.
memoize
(maxsize=None, keyfun=None, Cache=<class 'kombu.utils.functional.LRUCache'>)[source]¶ Decorator to cache function return value.
-
class
celery.utils.functional.
mlazy
(fun, *args, **kwargs)[source]¶ Memoized lazy evaluation.
The function is only evaluated once, every subsequent access will return the same value.
-
evaluated
= False¶ Set to
True
after the object has been evaluated.
-
-
celery.utils.functional.
noop
(*args, **kwargs)[source]¶ No operation.
Takes any arguments/keyword arguments and does nothing.
-
celery.utils.functional.
padlist
(container, size, default=None)[source]¶ Pad list with default elements.
Example
>>> first, last, city = padlist(['George', 'Costanza', 'NYC'], 3) ('George', 'Costanza', 'NYC') >>> first, last, city = padlist(['George', 'Costanza'], 3) ('George', 'Costanza', None) >>> first, last, city, planet = padlist( ... ['George', 'Costanza', 'NYC'], 4, default='Earth', ... ) ('George', 'Costanza', 'NYC', 'Earth')