structures.rst

Structures

The following is a guide to all the data structures that Satella defines.

Heap

This essentially allows you to have a heap object that will pretty much behave like the heapq library.

SetHeap

A heap with additional invariant that no two elements on the heap are the same. This is optimized for fast pushes() and membership checks.

TimeBasedHeap

Time-based heap is a good structure if you have many callbacks set to fire at a particular time in the future. It functions very like a normal Heap.

typednamedtuple

It's a named tuple, but it has typed fields. You will get a TypeError if you try to assign something else there.

OmniHashableMixin

If you need quick __hash__ and __eq__ operators from listed fields of the class.

Singleton

Makes the resulting object's __init__() be called at most once, then caches the object and returns the same upon each instantiation.

SingletonWithRegardsTo

Sometimes you just need an almost-singleton class, ie. class whose instance will depend on first n arguments. This function makes it easy:

It will remember instances already created and return you a previously created instance, keying on the first n arguments.

DictObject

DictObject is an object constructed out of a dict, that allows it's values to be obtained as getattr(), and not only getitem().

You can use the following function to recursively turn every dict into a DictObject

Immutable

Make your classes immutable. Normal assignment is only supported in the constructor, anywhere else it's a TypeError.

Immutable inherits from abc.ABCMeta, so it's safe to use abstract base classes here.

class Test(Immutable, metaclass=ABCMeta):

    attr: str = None

    def __init__(self):
        self.attr = 'value'

    def illegal_op(self):
        self.attr = 'test'  # this will TypeError

frozendict

A dictionary that can't be modified. I didn't import the one from _frozendict PyPI package, because it failed on Python 3.9. It is additionally hashable and __eq__-able