Transcrypt is a tool to precompile a fairly extensive subset of Python into compact, readable Javascript. It has the following characteristics:

- Allows for classical OO programming with *multiple inheritance* using pure Python syntax, parsed by CPython's native parser
- Seamless integration with the universe of high-quality web-oriented JavaScript libraries, rather than the desktop-oriented Python ones
- Hierarchical URL based module system to prevent name conflicts
- Simple relation between Python source and generated JavaScript code for easy debugging
- Multi-level sourcemaps and optional annotation of target code with source references
- Compact downloads, kB's rather than MB's
- Lightning fast JavaScript code, using memoization (call caching) to optionally bypass the prototype lookup chain
- Operator overloading can be switched on and off locally to facilitate use for numerical math that's both readable and efficient

.. figure:: http://www.transcrypt.org/illustrations/logo_white_small.png
	:alt: Logo
	
	**Transcription once used to be manual labour**
	
Documentation with code examples
================================

Take a look at the documentation with code examples at the Transcrypt website: http://www.transcrypt.org .

Status
======

Second release: Multi-level sourcemaps, annotated target code, virtualenv installation.
Automated tests of functionality of compiled code OK.
Reasonable amount of manual testing of the use of sourcemaps done by author.
Further tests and feedback very welcome, especially of the source maps part.
Sourcemaps were tested on Chrome under Windows and Linux, but seem to work on Firefox under Linux as well.

What's new
==========

- Installation procedure changed to benefit from virtualenv
- Optional annotation of target code with source file names and source line numbers
- Multi-level sourcemaps: Python source level debugging of both formatted and minified JavaScript code
- Source code included in map rather than separate as was the case earlier
- Switched from sectored V3 sourcemaps to monolithic V3 sourcemaps since they seem more mature and accepted

Known restrictions
==================

- No standard libs, use or encapsulate the JavaScript ones, that's part of the concept. Some may be ported though.
- Not all methods of builtin types are there by default. This results from a deliberate choice to keep Transcrypt lean. Such things can be distributed in separate libs.
- No eval and exec of Python code. This is again part of the concept. Transcrypt code is compiled, optimized and minified in advance to warant fast page loads.
- No threading of any kind. Will probably stay that way as long as JavaScript doesn't properly support that.
- No iterator, generator, xrange stuff. Maybe in the future if a broadly installed version of JavaScript suppports it.

Known bugs
==========

- None

Readability
===========

As can be seen below, there's a simple parallel between the Python and the JavaScript code.
So it should be easy to debug.
Also, code can be tested from the command prompt using stubs.

.. figure:: http://www.transcrypt.org/illustrations/class_compare.png
	:alt: Screenshot of Python versus JavaScript code
	
	**Classic OO with multiple inheritance in JavaScript**

Other packages you might like
=============================

- Multi-module Python source code obfuscator: https://pypi.python.org/pypi/Opy
- PLC simulator with Arduino code generation: https://pypi.python.org/pypi/SimPyLC
- A lightweight Python course taking beginners seriously (under construction): https://pypi.python.org/pypi/LightOn
- Event driven evaluation nodes: https://pypi.python.org/pypi/Eden
- Numscrypt (under construction, very early stage), experimental port of a microscopic part of NumPy to Transcrypt, using JavaScript typed arrays: https://pypi.python.org/pypi/Numscrypt
