x-strings

Extend Python syntax by defining custom string prefix. Provide function that transforms strings with your prefix.

This corresponds to Tagged Template Literals feature in JavaScript.

This project is only a toy. Technique used here shouldn't be considered as a good coding practice due to the fact how it is implemented. I don't recommend using it in production code. Hopefully it can be inspiring though.

Features

• Multiple encodings can be defined
• Multiple prefixes can be defined
• Prefixes can have more that one letter
• Encodings can take arguments (captured by regex)
• Doesn't corrupt Python syntax-error messages

Examples

Simple example is shown below.

app.py:

# coding: x-strings
print(x"Hello World")

launcher.py:

import xstrings
xstrings.register({'x': lambda t: t + "!!!"})

import app

Notice exclamation marks added to the end of the message:

$ python3 -B examples/launcher.py
Hello World!!!

This and more advanced examples can be found in here.

Caching

By default Python stores decoded code in __pycache__. Source file needs to be changed to get cache re-generated. This may complicate development of launcher.py. You can prevent Python from generating cache by either:

• Setting env var: PYTHONDONTWRITEBYTECODE to 1
• Using -B switch for python
• Calling sys.dont_write_bytecode = True in the code

References

Project is inspired by pyxl4.