Python Implementations
An "implementation" of Python should be taken to mean a program or environment which provides support for the execution of programs written in the Python language, as represented by the CPython reference implementation.
There have been and are several distinct software packages providing of what we all recognize as Python, although some of those are more like distributions or variants of some existing implementation than a completely new implementation of the language.
- IronPython
- Jython
- Transcrypt
IronPython
Open-source implementation for .NET and Mono written in C#, licensed under Apache License 2.0. It relies on DLR
(Dynamic Language Runtime). It supports only version 2.7, version 3 is currently being developed.
Differences with CPython:
- Tight integration with .NET Framework.
- Strings are Unicode by default.
- Does not support extensions for CPython written in C.
- Does not suffer from Global Interpreter Lock.
- Performance is usually lower, though it depends on tests.
Hello World
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- print "Hello World!"
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- import clr
- from System import Console
- Console.WriteLine("Hello World!")
- Official website
- GitHub repository
Jython
Open-source implementation for JVM written in Java, licensed under Python Software Foundation License. It supports only version 2.7, version 3 is currently being developed.
Differences with CPython:
- Tight integration with JVM.
- Strings are Unicode.
- Does not support extensions for CPython written in C.
- Does not suffer from Global Interpreter Lock.
- Performance is usually lower, though it depends on tests.
Hello World
print "Hello World!"
You can also use Java functions:
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- from java.lang import System
- System.out.println("Hello World!")
- Official website
- Mercurial repository
Transcrypt
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 allowing module distribution via PyPi
- 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
- Optimized JavaScript code, using memoization (call caching) to optionally bypass the prototype
lookup chain - Operator overloading can be switched on and off locally to facilitate readable numerical math
Code size and speed
Experience has shown that 650 kB of Python source code roughly translates in the same amount of JavaScript source code. The speed matches the speed of handwritten JavaScript and can surpass it if call memoizing is switched on.
Integration with HTML
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- <script src="__javascript__/hello.js"></script>
- <h2>Hello demo</h2>
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- <p>
- <div id = "greet">...</div>
- <button onclick="hello.solarSystem.greet ()">Click me repeatedly!</button>
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- <p>
- <div id = "explain">...</div>
- <button onclick="hello.solarSystem.explain ()">And click me repeatedly too!</button>
class SolarSystem:
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- planets =[list (chain (planet, (index + 1,))) for index, planet in enumerate ((
- ('Mercury', 'hot', 2240),
- ('Venus', 'sulphurous', 6052),
- ('Earth', 'fertile', 6378),
- ('Mars', 'reddish', 3397),
- ('Jupiter', 'stormy', 71492),
- ('Saturn', 'ringed', 60268),
- ('Uranus', 'cold', 25559),
- ('Neptune', 'very cold', 24766)
- ))]
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- lines = (
- '{} is a {} planet',
- 'The radius of {} is {} km',
- '{} is planet nr. {} counting from the sun'
- )
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- def __init__ (self):
- self.lineIndex = 0
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- def greet (self):
- self.planet = self.planets [int (Math.random () * len (self.planets))]
- document.getElementById ('greet') .innerHTML = 'Hello {}'.format (self.planet [0])
- self.explain ()
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- def explain (self):
- document.getElementById ('explain').innerHTML = (
- self.lines [self.lineIndex] .format (self.planet [0], self.planet [self.lineIndex + 1])
- )
- self.lineIndex = (self.lineIndex + 1) % 3
- solarSystem = SolarSystem ()
Transcrypt can be used in combination with any JavaScript library without special measures or syntax. In the documentation, examples are given for a.o. react.js, riot.js, fabric.js and node.js.
Relation between Python and JavaScript code
Python
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- class A:
- def __init__ (self, x):
- self.x = x
- def show (self, label):
- print ('A.show', label, self.x)
- class B:
- def __init__ (self, y):
- alert ('In B constructor')
- self.y = y
- def show (self, label):
- print ('B.show', label, self.y)
- class C (A, B):
- def __init__ (self, x, y):
- alert ('In C constructor')
- A.__init__ (self, x)
- B.__init__ (self, y)
- self.show ('constructor')
- def show (self, label):
- B.show (self, label)
- print ('C.show', label, self.x, self.y)
- a = A (1001)
- a.show ('america')
- b = B (2002)
- b.show ('russia')
- c = C (3003, 4004)
- c.show ('netherlands')
- show2 = c.show
- show2 ('copy')
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- var A = __class__ ('A', [object], {
- get __init__ () {return __get__ (this, function (self, x) {
- self.x = x;
- });},
- get show () {return __get__ (this, function (self, label) {
- print ('A.show', label, self.x);
- });}
- });
- var B = __class__ ('B', [object], {
- get __init__ () {return __get__ (this, function (self, y) {
- alert ('In B constructor');
- self.y = y;
- });},
- get show () {return __get__ (this, function (self, label) {
- print ('B.show', label, self.y);
- });}
- });
- var C = __class__ ('C', [A, B], {
- get __init__ () {return __get__ (this, function (self, x, y) {
- alert ('In C constructor');
- A.__init__ (self, x);
- B.__init__ (self, y);
- self.show ('constructor');
- });},
- get show () {return __get__ (this, function (self, label) {
- B.show (self, label);
- print ('C.show', label, self.x, self.y);
- });}
- });
- var a = A (1001);
- a.show ('america');
- var b = B (2002);
- b.show ('russia');
- var c = C (3003, 4004);
- c.show ('netherlands');
- var show2 = c.show;
- show2 ('copy');