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Python to JavaScript transpiler, supporting multiple inheritance and generating lean, highly readable code

Project description

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
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 of latest release

Release 7 (version 3.5.213):

This release features

  • Parameterless and parametrized function and class decorators
  • Transcrypt’s ‘in’ operator expanded to work on JavaScript objects as well, for better integration of Python dicts and JavaScript objects, especially literals
  • Else clause for exceptions added
  • Complex numbers
  • The cmath library has been added in preparation of expansion of NumScrypt, a.o. with (I)FFT and in general in making Transcrypt suitable for interactively demonstrating low volume scientific and technical computations in the browser.
  • Documentation and autotest expanded accordingly
  • Several bugs fixed

Thanks to anyone who contributed!

Jacques de Hooge

What’s new in the latest commits

  • Optional static type validation using mypy (experimental)
  • Small doc improvements
  • Some more fixes for Numscrypt
  • Fix to enable Numscrypt development
  • *args now also can be used in calling pure javascript methods (see issue #102)
  • Pragma’s else and elif fixed for use in .py rather than .js files
  • Release 7
  • Module cmath added + autotest
  • Else-clause for exceptions added
  • Complex numbers added + autotest (no cmath module yet)
  • Transcrypt’s ‘in’ operator now also works on objects for better integration of Python dicts and JavaScript objects, especially literals
  • Class decorators added + autotest
  • Function decorators with parameters + autotest
  • Parameterless function decorators + autotest
  • Release 6
  • Docs updated
  • Local classes added + autotest
  • Dict method pop added, setdefault fixed + autotest for both
  • Time module added + autotest + shipment test
  • String split and rsplit fixed
  • Export all imports
  • Added: any, all, assert
  • Readme adapted
  • Workaround for console.log.apply removed
  • Several small fixes
  • Itertools now functionally complete, except for zip_longest. First breed of autotests added for it. Some func’s still relies on seq’s rather than iter’s.
  • Added: __pragma__ (‘ifndef’), __pragma__ (‘else’)
  • Doc’s updated, empty your browser cache and read about the newest facilities on-line
  • Shipment test expanded with es6 compilation
  • Conditional compilation pragma’s added to facilitate optional es6 autotesting
  • Generators, yield and es6 compilation added + testcases, while retaining es5 compatible minified output
  • Compilation for node.js fixed
  • Blending between Python and JavaScript exceptions
  • Swallowing of unrecognized exceptions fixed
  • Iterator protocol supported

Known restrictions

  • Only a very limited selection of standard libs have been chosen for inclusion in the Transcrypt distribution. Use or encapsulate the JavaScript ones, that’s part of the concept. Some additional standard libs may be ported in the future though.
  • A few methods of builtin types are currently left out, especially when they (almost) duplicate functionality of other methods. Also method decorators (as opposed to function decorators and class decorators) are not supported, with the exception of @classmethod. This results from a deliberate choice to keep Transcrypt lean and simple.
  • 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. In this respect its design goal is fundamentally different from tools that compile on the fly in the browser. Transcrypt is targeted towards building professional, extensive, real world web applications that load and run as fast as their JavaScript counterparts, but offers Pythonically clean, modular structure and maintainability.
  • No threading of any kind. Will probably stay that way as long as JavaScript doesn’t properly support that.

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.

Screenshot of Python versus JavaScript code

Classic OO with multiple inheritance in JavaScript

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Licence

Copyright 2014, 2015, 2016 Jacques de Hooge, GEATEC engineering, www.geatec.com

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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