Simple Example

from auto_init import AutoInitContext

ctx = AutoInitContext()
p: Point = ctx.get_instance(Point)
assert p.x == 0
assert p.y == 0
assert p.z is None

Note that the Point class could also be a dataclass and it would work too.

Not So Simple Example

import logging

from auto_init import AutoInitContext


class Worker:
    enterprise: "Enterprise"
    log: logging.Logger


class Reporter:
    enterprise: "Enterprise"
    log: logging.Logger


class Enterprise:
    worker: Worker
    reporter: Reporter


ctx = AutoInitContext()
ctx.register_instance(logging.getLogger(__name__))
ctx.register_singleton(Enterprise)

enterprise: Enterprise = ctx.get_instance(Enterprise)
assert enterprise.worker.log is enterprise.reporter.log
assert enterprise.worker.enterprise is enterprise
assert enterprise.reporter.enterprise is enterprise

v0.0.5

• Supports initialising attributes annotated with typing.List and typing.Dict as empty lists or dictionaries. Other typing.*-annotated attributes are initialised as None.

• Do not attempt to get type hints from typing.* classes, it raises exceptions in Python 3.7 and does not return anything useful in Python 3.6 anyway.

• Fixes dependencies for Python 3.6, removes unnecessary contextvars and dataclasses dependencies for Python 3.7.

• Travis CI setup.

v0.0.4

• Complete rewrite to deal with circular references. Intrusive approach is no good.

• Forward references in type hints don’t really work in Python 3.7 even with futures. Let’s use Python 3.6.

v0.0.3

• Added AutoInitContext.explicit_only – allows marking the context as only initialising the types with specified providers and leaving all others untouched.

• If a type hint includes a default value (declares a class attribute) then the corresponding instance attribute will be a copy by reference of the class attribute unless there is an explicit provider specified in the context. This means that x: int = None will be initialised as None, not as 0.

v0.0.2

• Non-intrusive auto-init: function auto_init and method AutoInitContext.auto_init that initialises instances without making any changes to user’s classes.

• Added AutoInitContext.singleton_types – allows to specify singleton types non-intrusively.