This document describes the current stable version of Celery (4.4). For development docs, go here.
celery.utils.functional
¶
Functional-style utilties.
-
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. -
iteritems
()¶
-
iterkeys
()¶
-
itervalues
()¶
-
popitem
() → (k, v), remove and return some (key, value) pair[source]¶ as a 2-tuple; but raise KeyError if D is empty.
-
-
celery.utils.functional.
is_list
(l, 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.
-
celery.utils.functional.
maybe_list
(l, 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.
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.
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.
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')
-
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.
regen
(it)[source]¶ Convert iterator to an object that can be consumed multiple times.
Regen
takes any iterable, and if the object is an generator it will cache the evaluated list on first access, so that the generator can be “consumed” multiple times.
-
celery.utils.functional.
dictfilter
(d=None, **kw)[source]¶ Remove all keys from dict
d
whose value isNone
.
-
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.
maybe_evaluate
(value)[source]¶ Evaluate value only if value is a
lazy
instance.