CobraScript

Simple experiment of translate basic python ast to javascript with output than can be read by humans (it works like coffescript, but with python syntax).

Warning: this package is in alpha stage of development.

Install

CobraScript itself is written in python and a main installation source is from PyPI (python package index):

pip install cobrascript

Command line

usage: cobrascript [-h] [-g] [-w] [-o outputfile.js] [-b] [-j]
                   [--indent INDENT] [--auto-camelcase]
                   input.py [input.py ...]

Python to Javascript translator.

positional arguments:
  input.py              A list of python files for translate.

optional arguments:
  -h, --help            show this help message and exit
  -g, --debug           Activate debug mode (only for developers).
  -w, --warnings        Show static analizer warnings.
  -o outputfile.js, --output outputfile.js
                        Set output file (by default is stdout).
  -b, --bare            Compile without a toplevel closure.
  -j, --join            Join python files before compile.
  --indent INDENT       Set default output indentation level.
  --auto-camelcase      Convert all identifiers to camel case.

Overview

Assignment

CobraScript/Python:

somenumber = 22
some_string = "Hello"

Javascript:

var somenumber, some_string;
somenumber = 22;
some_string = "Hello";

Lists & Dicts

CobraScript/Python:

mylist = [1, 2, 3, 4]

mydict = {
    "foo": 1,
    "bar": [2,3,4]
}

Javascript:

var mylist, mydict;
mylist = [1,2,3,4];
mydict = {
    "foo": 1,
    "bar": [1,2,3]
}

Functions & Lambdas

CobraScript/Python:

func1 = lambda x: x*2

def func2():
    return 2

Javascript:

var func1, func2;

func1 = function(x) {
    return x*2;
}
func2 = function() {
    return 2;
}

If, Elif and Else

CobraScript/Python:

if x > y:
    return x
elif x < y:
    return y
else:
    return 0

Javascript:

if (x > y) {
    return x;
} else if (x < y) {
    return y;
} else {
    return 0;
}

For loop

CobraScript/Python:

for item in [1,2,3,4,5]:
    console.log(item)

Javascript:

var item, ref_0, ref_1;
for (ref_0 = 0, ref_1 = [1,2,3,4,5]; ref_0 < ref_1.length; ref_0++) {
    item = ref_1[ref_0];
    console.log(item);
}

While loop

CobraScript/Python:

while 2 > a:
    console.log(1)

Javascript:

while (2 > a) {
    console.log(1);
}

Multiple assignation

CobraScript/Python:

a, b = 1, 2

Javascript:

var _ref_0;
_ref_0 = [1,2];
a = _ref_0[0];
b = _ref_0[1];

Decorators

CobraScript/Python:

def debug(func):
    def _decorator():
        console.log("call....")
        return func.apply(null, arguments)

    return _decorator

@debug
def sum(a1, a2, a3):
    return a1 + a2 + a3

console.log(sum(1,2,3))

Javascript:

var debug, sum;
debug = function(func) {
    var _decorator;
    _decorator = function() {
        console.log("call....");
        return func.apply(null, arguments);
    };
    return _decorator;
};
sum = function(a1, a2, a3) {
    return (a1 + a2) + a3;
};
sum = debug(sum);
console.log(sum(1, 2, 3));

Operators

This is a equivalence table between python operators and translated javascript operators:

CobraScript	JavaScript
is	===
==	===
!=	!==
and	&&
or	||

Global object

This part is slighty distinct from others, because follows python philosofy: "explicit better than implicit".

For expose some variables to global scope, you should import _global module (special form module).

Example:

# example_file.py

import _global as g

# g represents a window object
g.some_variable = 2

And this is translated to:

// example_file.js
(function()
    var g;
    g = this;
    g.some_variable = 2;
}).call(this);

New operator

Python as is does not suport new operator. For emulate javascript new operator, cobrascript exposes other special-form import thar exposes "magic" function that emulates a new operator.

Example:

import _new as new_instance
defer = new_instance(SomeClass, "param1", "param2")

And, this is translated to:

(function() {
    var defer, new_instance;
    new_instance = function() { //
        // Some special function for call new.
        // (For full function definition, you can see
        //  tests code)
    };

    defer = new_instance(SomeClass, "param1", "param2");
}).call(this);

Full list of implemented features

Translation

• Variable assignation.
• Multiple variable assignation.
• Binary and Logical operators.
• Functions, Lambdas and Nested functions.
• Dicts and Lists.
• Function calls.
• Decorators.
• Positional arguments.
• For and while loops.
• List comprensions.
• Try/Except/Finally statements.
• Explicit global object.
• Explicit new function for create object.
• Multiple assignation.

Static Analisys

• Lexycal scope handling.
• Protection for overwrite imported special forms.

Command line

• Bare mode: compile module without wrapped closure
• Join: join multiple files before compile.
• Auto CamelCase: convert identifieres automatically from snake case to camel case.

Pending to implement

• Classes with hineritance.
• Dict comprensions.
• Variable arguments.

License

Copyright (c) 2013 Andrey Antukh <[email protected]>
Copyright (c) 2013 Jesús Espino García <[email protected]>

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.