heliclockter

Heliclockter

heliclockter is a robust way of dealing with datetimes and timestamps in python. It is statically type checkable as well as runtime enforceable and integrates with pydantic.

The library exposes 3 classes:

• datetime_tz, a datetime ensured to be timezone-aware.
• datetime_local, a datetime ensured to be timezone-aware in the local timezone.
• datetime_utc, a datetime ensured to be timezone-aware in the UTC+0 timezone.

as well as various utilities to instantiate, mutate and serialize those classes.

See our announcement post for a more background on why we wrote heliclockter.

Examples

Say you want to create a timestamp of the current time in the UTC+0 timezone.

from heliclockter import datetime_utc

now = datetime_utc.now()
# datetime_utc(2022, 11, 4, 15, 28, 10, 478176, tzinfo=zoneinfo.ZoneInfo(key='UTC'))

Or imagine you want to create a timestamp 2 hours in the future from now:

from heliclockter import datetime_utc

two_hours_from_now = datetime_utc.future(hours=2)
# datetime_utc(2022, 11, 4, 17, 28, 52, 478176, tzinfo=zoneinfo.ZoneInfo(key='UTC'))

Features

• Runtime enforcable timezone-aware datetimes
• Utilities for instantiating, mutating and serializing timezone-aware datetimes
• Statically type check-ble
• Pydantic integration
• Extensive test suite
• No third party dependencies

Installation

To install heliclockter, simply:

$ pip install heliclockter

More examples

Imagine you want to parse a JSON response from a third party API which includes a timestamp, and you want to handle the timestamp in the UTC+0 timezone regardless of how the 3rd party relays it. This can easily be done with pydantic and heliclockter:

import requests
from pydantic import BaseModel
from heliclockter import datetime_utc


class ApiResponse(BaseModel):
    current_time: datetime_utc


def get_response() -> ApiResponse:
    response = requests.get('https://some-api.com/time')
    return ApiResponse.parse_obj(response.json())

The returned ApiResponse instance is guaranteed to have parsed the current_time attribute as UTC+0 no matter how the api provided the timestamp. If no timezone information is provided, it will be assumed to be UTC+0.

Expanding the module can be done with little effort, by creating a new class that inherits datetime_tz:

from zoneinfo import ZoneInfo
from heliclockter import datetime_tz


class datetime_cet(datetime_tz):
    """
    A `datetime_cet` is a `datetime_tz` but which is guaranteed to be in the 'CET' timezone.
    """

    assumed_timezone_for_timezone_naive_input = ZoneInfo('CET')

If you have a timestamp which is naive, but the timezone in which it is made is known to you, you can easily create a datetime_tz instance using your own defined classes:

aware_dt = datetime_cet.strptime('2022-11-04T15:49:29', '%Y-%m-%dT%H:%M:%S')
# datetime_cet(2022, 11, 4, 15, 49, 29, tzinfo=zoneinfo.ZoneInfo(key='CET'))

About the name

heliclockter is a word play of "clock" and "helicopter". The module aims to guide the user and help them make little to no mistakes when handling datetimes, just like a helicopter parent strictly supervises their children.