Import Python modules from dicts and JSON formatted documents

Paker

Paker is module for importing Python packages/modules from dictionaries and JSON formatted documents. It was inspired by httpimporter.

Installation

From PyPI

pip install paker

From source

git clone https://github.com/desty2k/paker.git
cd paker
pip install .

Usage

In Python script

You can import Python modules directly from string, dict or bytes (without disk IO).

import paker
import logging

MODULE = {"somemodule": {"type": "module", "code": "fun = lambda x: x**2"}}
logging.basicConfig(level=logging.NOTSET)

if __name__ == '__main__':
    with paker.loads(MODULE) as loader:
        # somemodule will be available only in this context
        from somemodule import fun
        assert fun(2), 4
        assert fun(5), 25
        print("6**2 is {}".format(fun(6)))
        print("It works!")

To import modules from .json files use load function. In this example paker will serialize and import mss package.

import paker
import logging

file = "mss.json"
logging.basicConfig(level=logging.NOTSET)

# install mss using `pip install mss`
# serialize module
with open(file, "w+") as f:
    paker.dump("mss", f, indent=4)

# now you can uninstall mss using `pip uninstall mss -y`
# load package back from dump file
with open(file, "r") as f:
    loader = paker.load(f)

import mss
with mss.mss() as sct:
    sct.shot()

# remove loader and clean the cache
loader.unload()

try:
    # this will throw error
    import mss
except ImportError:
    print("mss unloaded successfully!")

CLI

Paker can also work as a standalone script. To dump module to JSON dict use dump command:

paker dump mss

To recreate module from JSON dict use load:

paker load mss.json

Show all modules and packages in .json file

paker list mss.json

How it works

When importing modules or packages Python iterates over importers in sys.meta_path and calls find_module method on each object. If the importer returns self, it means that the module can be imported and None means that importer did not find searched package. If any importer has confirmed the ability to import module, Python executes another method on it - load_module. Paker implements its own importer called jsonimporter, which instead of searching for modules in directories, looks for them in Python dictionaries

To dump module or package to JSON document, Paker recursively iterates over modules and creates dict with code and type of each module and submodules if object is package.

GitHub

https://github.com/desty2k/paker