Python Mini Racer

Minimal, modern embedded V8 for Python.

Free software: ISC license

Features

Unicode support
Thread safe
Re-usable contexts
Binary object is Python agnostic

MiniRacer can be easily used by Django or Flask projects to minify assets, run babel or compile CoffeeScript.

Examples

py_mini_racer is straightforward to use:

>>> from py_mini_racer import py_mini_racer
>>> ctx = py_mini_racer.MiniRacer()
>>> ctx.eval('1+1')
2
>>> ctx.eval("var x = {company: 'Sqreen'}; x.company")
u'Sqreen'
>>> print ctx.eval(u"'\N{HEAVY BLACK HEART}'")
❤
>>> ctx.eval("var fun = () => ({ foo: 1 });")
>>> ctx.call("fun")
{u'foo': 1}

Variables are kept inside of a context:

>>> ctx.eval("x.company")
u'Sqreen'

You can give directly a custom JSON encoder when sending non-JSON encodable parameters:

import json

from datetime import datetime

class CustomEncoder(json.JSONEncoder):

        def default(self, obj):
            if isinstance(obj, datetime):
                return obj.isoformat()

            return json.JSONEncoder.default(self, obj)

>>> ctx.eval("var f = function(args) { return args; }")
>>> ctx.call("f", datetime.now(), encoder=CustomEncoder)
u'2017-03-31T16:51:02.474118'

PyMiniRacer is ES6 capable:

>>> ctx.eval("[1,2,3].includes(5)")
False

V8 heap information can be retrieved:

>>> ctx.heap_stats()
{u'total_physical_size': 1613896,
 u'used_heap_size': 1512520,
 u'total_heap_size': 3997696,
 u'total_heap_size_executable': 3145728,
 u'heap_size_limit': 1501560832}

Compatibility

PyMiniRacer is compatible with Python 2 and Python 3. Wheels are generated for python 2.7 and python 3.4 to python 3.6.

Binary builds availability

The PyMiniRacer binary builds have been tested on x86_64 with:

OSX 10.10
Ubuntu >= 12.04
Debian >= 7
CentOS >= 6

You need pip >= 8.1 to install the wheels - you can check and upgrade yours in this way:

$ pip --version
$ pip install --upgrade pip

It should work on any Linux with a libc >= 2.12 and a wheel compatible pip (>= 8.1).

If you have a up-to-date pip and it doesn't use a wheel, you might have an environment for which no wheel is built. Please open an issue.

Installation

We built Python wheels (prebuilt binaries) for OSX 64 bits and Linux 64 bits - most recent distributions. You need pip >= 1.4 and setuptools >= 0.8.

$ pip install py-mini-racer

Build

You can build v8 with the command:

$ python setup.py build_v8

You can also build the ctype extension:

$ python setup.py build_ext

Which automatically builds v8.

You can generate a wheel with the command:

$ python setup.py bdist_wheel

which builds v8, the extension, and generates a wheel.

Notes for building on OSX

The legacy Python binary builds (OSX 10.6) need to be downloaded from:: https://www.python.org/downloads/

They will allow to build a wheel compatible with former OSX versions.

Tests

If you want to run the tests, you need to build V8 first, then launch:

$ python setup.py test --addopts tests

Credits

Built with love by Sqreen.

PyMiniRacer launch was described in this blog post.

PyMiniRacer is inspired by mini_racer, built for the Ruby world by Sam Saffron.

Tools used in rendering this package:

Todo

Export V8 version. Fix circular structures export.

johnnoone/PyMiniRacer