semvec/pypi-packages huggingface dataset:
fastenum 1.1.2
Faster drop-in replacement of Python's enum
License: Apache 2.0
Requires Python: <4.0,>=3.10

# fastenum

A roughly 3x faster drop-in replacement of Python's ``enum``.


## Why

Python's [`enum`](https://docs.python.org/3/library/enum.html) type is a useful building block for creating semantic types and constants in your programs.

The problem is, if you're doing millions and millions of enum lookups (even simple expressions like `Color.ORANGE`) it's a little bit slow.

`fastenum` is a stripped-down enum implementation that's up to 3.5x faster than the standard library implementation. At [Quantlane](https://quantlane.com) we use it in production code as a drop-in replacement. Read more, including benchmarks, on our blog: [A 3x faster enum type for Python](https://quantlane.com/blog/fastenum/).


## Installation

`fastenum` is [available on PyPI](https://pypi.org/project/fastenum/) and you can install it with:

```shell
pip install fastenum
```

or

```shell
poetry add fastenum
```

## How to use it

Simply use `fastenum.Enum` instead of `enum.Enum`:

```python
import fastenum

class Color(fastenum.Enum):
    RED = 0
    BLUE = 1
    GREEN = 2

assert isinstance(Color.RED, Color)
assert Color.RED is Color['RED']
assert Color.BLUE != 1
assert Color.GREEN.value == 2

def is_red(c: Color) -> bool:
    return c is Color.RED
```

There is also a mypy plugin that you'll want to enable in `mypy.ini` to help mypy understand `fastenum` just like it understands `enum`:

```ini
[mypy]
plugins = fastenum.mypy_plugin:plugin
```


## Tradeoffs and disadvantages

There is no support for automatic values, unique value checks, aliases, custom `__init__` implementations on members, `IntEnum`, `Flag`, or the functional API. If you require any of these features it's probably best to just use `enum`.

`fastenum`'s mypy plugin may cause issues with your mypy cache (see above).


## Running tests & benchmarks

```shell
poetry install
poetry run pytest
```

## Contributing

Pull requests are welcome!

We will accept pull requests adding missing functionality *provided* they do not impact base `fastenum` performance (it's best to verify that with benchmarks).

---

![](quantlane.png)

> `fastenum` was made by `Quantlane <https://quantlane.com>`_, a systematic trading firm.
> We design, build and run our own stock trading platform.