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Brython: Not Celtic, Pythonic!

What

Where

When

 It's alive

Changes in Brython version 2.0-20140209-164925

Backwards-incompatible change

Features

• - namespace isolation : in previous versions, the names defined in Brython core scripts were included in the global Javascript namespace, raising risks of conflict with names defined in Javascript programs or libraries. In this version, the only names included in the global Javascript namespace are __BRYTHON__ (used internally) and brython(), the function called on page load
• - implement sys.implementation with values adapted for Brython
• - allow syntax del (x, y, z)
• - use Dan McDougall's pyminifier to reduce size of py_VFS.js
• - make_dist generates a script brython_dist.js that can be used as a standalone distribution on a centralised server.

Demos

• - add drop files demo (by Glenn Linderman) and French Python course (using module slideshow) to the gallery

Imports

• - improved version of py_VFS.js by Billy Earney. py_VFS compiles the standard library to make imports faster. Now packs Python source with JSON instead of base64

Built-in modules

• - browser : add attributes "window" and "document" as alias of respectively "win" and "doc"
• - add a module browser/slideshow for PowerPoint-like slideshows in Brython, using a custom file format

Bug fixes

• - issue #174 : string format character % has wrong precedence
• - issue #175 : Functions should return None by default
• - issue #183 : re.findall() broken
• - issue #198 : operator precedence not defined for << and >>
• - issue #206 : add <noscript> in case Javascript is disabled
• - issue #208 : bug with try / else
• - issue #209 : bug in ternary operator
• - function definions must be evaluated only once, upon function definition
• - bug with del a[:]
• - bug with dir() called without arguments
• - bug in map()
• - bug with "func(x=1,)" ; "return +x" ; "func(10*-x)"
• - bug in divmod and round
• - bug in local_storage method keys()
• - add attribute __doc__ to class and instance methods

Documentation

• - updated with the changes introduced in this version
• - add documentation for the built-in module javascript
• - translation in Spanish updated by Kiko Correoso

Hands on Python

Attributes, Properties and Descriptors

Download Brython

Changes

Bugs

• - bug fixes :

Other

• package organisation : move JSObject from py_dom.js to py_utils.js
• gallery : add a demo of a solitaire game using SVG drag and drop

Feedback

Brython modes

The Brython interactive mode

<iframe src="http://www.brython.info/console.html" width="98%" height="400">Sorry... your browser doesn't support iframe. Time to upgrade or go to <a href="http://www.brython.info/console.html">http://www.brython.info/console.html</a> in a separate tab.</iframe>

x = input("yo")

print(x)

import webbrowser

webbrowser.open("http://en.wikipedia.com/wiki/internet_" + x*2)

doc <= "think"

If you've been following my blog, you already know about the <= (left arrow) operator. If not, check it out here: http://raspberry-python.blogspot.com/2012/12/brython-browser-python.html

Site

em portugues!

Documentação

Grupo

Grâce a Brython

L’icône Brython GPS

Une vraie app pour iPhone?

Splash (ancienne carte de Caroline du Nord)

Le premier écran, mode manuel

Mode mise a jour automatique

J'essaie?

J'ai déjà vu cela, non?

Notre HTML

Notre Python

# globals #########################
refr = False
geo = win.navigator.geolocation
watchid = 0


# les fonctions ###########################
def navi(pos):
    xyz = pos.coords

    ul = UL(id="nav")
    ul <= LI('lat: %s' % xyz.latitude)
    ul <= LI('lon: %s' % xyz.longitude)

    mapurl = "http://maps.googleapis.com/maps/api/staticmap?markers=%f,%f&zoom=15&size=320x298&sensor=true" % (xyz.latitude, xyz.longitude)
    img = IMG(src = mapurl, id = "map")
    try:
        doc["nav"].html = ul.html  # on met a jour la liste
    except KeyError:
        doc["navarea"] <= ul  # on cree la liste
    try:
        doc["map"].src = mapurl  # on met a jour l'url de l'image
    except KeyError:
        doc["maparea"] <= img  # on cree la balise img

def nonavi(error):
    log(error)

def navirefresh(ev):
    global refr, watchid
    refr = False if refr else True
    if refr == True:
        doc["switch"].className = "switch on"
        watchid = geo.watchPosition(navi, nonavi)
    else:
        doc["switch"].className = "switch"
        geo.clearWatch(watchid)

# au demarrage ###########
if geo:
    geo.getCurrentPosition(navi, nonavi)
    doc["switch"].className = "switch"
    doc["switch"].onclick = navirefresh  # on associe un evenement onclick
else:
    alert('geolocation not supported')

Notre CSS

Ce n'est que le début

Thanks to Brython

Brython GPS icon

Native? Not quite...

Splash page

Tracking my progress

Automatically refreshes on movement

Can I try it?

What makes it special?

The HTML

The Python

# globals #########################
refr = False
geo = win.navigator.geolocation
watchid = 0


# functions ###########################
def navi(pos):
    xyz = pos.coords

    ul = UL(id="nav")
    ul <= LI('lat: %s' % xyz.latitude)
    ul <= LI('lon: %s' % xyz.longitude)

    mapurl = "http://maps.googleapis.com/maps/api/staticmap?markers=%f,%f&zoom=15&size=320x298&sensor=true" % (xyz.latitude, xyz.longitude)
    img = IMG(src = mapurl, id = "map")
    try:
        doc["nav"].html = ul.html
    except KeyError:
        doc["navarea"] <= ul
    try:
        doc["map"].src = mapurl
    except KeyError:
        doc["maparea"] <= img

def nonavi(error):
    log(error)

def navirefresh(ev):
    global refr, watchid
    refr = False if refr else True
    if refr == True:
        doc["switch"].className = "switch on"
        watchid = geo.watchPosition(navi, nonavi)
    else:
        doc["switch"].className = "switch"
        geo.clearWatch(watchid)

# the setup
if geo:
    geo.getCurrentPosition(navi, nonavi)
    doc["switch"].className = "switch"
    doc["switch"].onclick = navirefresh
else:
    alert('geolocation not supported')

The CSS

The tip of the iceberg

Utopia

Navegadores Web

<script type="text/python">

def lista(num):

    for i in range(num):

        print(i)

lista(10)

</script>

<script type="text/python" src="codigo.py"></script>

Impossível!

Sur le serveur

Mais pourquoi le titre?

Python 2

machaine = u"je suis bien étonné, François!"

Encodage

#!/usr/bin/env python

# -*- coding: utf-8 -*-

#!/usr/bin/env python

# vim: set fileencoding=utf-8

Python 3

Brython

CYR =  'АБЦДЕФГЧИЙКЛМНОПЯРСТУВЖХЫЗШЩЭЮЁЬЪ'

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<script src="/brython.js"></script>
</head>
<body onload="brython()">
<h1>Phonetic cyrillic on QWERTY keyboard</h1>
Here is a little test, mapping latin characters on a keyboard to their phonetically equivalent characters in a cyrillic script, as used in Russian.
<p>
This demoes UTF-8 unicode, handling of keyboard events, and adding, modifying and deleting elements from the tree.
<script type="text/python">

"""
Phonetic ordering of cyrillic (фонетических упорядочение кириллицу)
We are matching the latin alphabet, uppercase, then lowercase
"""

CYR =  'АБЦДЕФГЧИЙКЛМНОПЯРСТУВЖХЫЗШЩЭЮЁЬЪабцдефгчийклмнопярстувжхызшщэюёьъ'
position = 0


def printkey(letter):
    global position
    try:
        span = doc[str(position)]
        span.value = letter
    except KeyError:
        doc <= SPAN(letter, id = str(position))
    position += 1


def deletekey():
    global position
    position -= 1
    if position < 0:
        position = 0
    else:
        del doc[str(position)]


def keydown(e):
    if not e:
        e = win.event
    key = e.keyCode
    offset = 65 if e.shiftKey else 32
    e.preventDefault()
    e.stopPropagation()
    log(key)
    if key == 8:
        deletekey()
    elif key == 32:
        printkey(' ')
    elif key in range(48, 58):
        printkey(str(key - 48))
    elif key >= offset:
        printkey(CYR[key - offset])


def keyup(e):
    if not e:
        e = win.event
    e.preventDefault()
    e.stopPropagation()


def drawkeyboard():
    table = TABLE()
    row = TR()
    for letter in CYR:
        row <= TD(BUTTON(letter, onClick= "printkey('%s')" % letter))
        if letter in ('Я','Ъ','я'):
            table <= row
            row=TR()
    table <= row
    doc <= table


# Draw keyboard and set key events

drawkeyboard()
doc.onkeydown = keydown
doc.onkeyup = keyup

</script>
<br />
Click buttons or type on keyboard:
<br />
</body>
</html>

Python vs Brython vs Javacript

The lightbulb moment

- for standard output there was a Brython-specific builtin function log() : it is now replaced by the usual Python function print(), with the syntax used in Python 3, including the keyword argument "end"
By default, print() sends its arguments to the browser console. This can be changed by setting sys.stdout to an object with a method write(). For instance, in the online console, to send the output to the textarea with the id "console" the code is (remember that classes are not implemented yet...)

import sys
sys.stdout = object()
def write(data):
    doc["console"].value += data
sys.stdout.write = write

sys.stderr = object()
sys.stderr.write = write

<!DOCTYPE html>
<html>
    <head>
        <title>Brython test</title>
        <script src="brython.js"></script>
    </head>
    <body onLoad="brython()">
        <script type="text/python">
        def printandprint():
            print("hello")
            win.print()

        doc <= BUTTON('Print and print', onClick='printandprint()')
        </script>
    </body>
</html>

Brython keywords

Geolocation

geo = win.navigator.geolocation

def navi(pos):
    log('Position acquired')
    xyz = pos.coords
    display = "Your position: %f,%f" % (xyz.latitude, xyz.longitude)
    alert(display)
    log(pos.timestamp)
    log(xyz.latitude)
    log(xyz.longitude)
    log(xyz.accuracy)
    log(xyz.altitude)
    log(xyz.altitudeAccuracy)
    log(xyz.heading)
    log(xyz.speed)

def nonavi(error):
    log(error)

if geo:
    geo.getCurrentPosition(navi, nonavi)
else:
    alert('geolocation not supported')

Full code

Brython improvements

New this week

x = 7 if a > 2 else 17

y = [ x ** 2 for x in range(10)]

<!DOCTYPE html>
<html>
    <head>
        <title>Brython test</title>
        <script src="brython.js"></script>
    </head>
    <body onLoad="brython()">
        <script type="text/python">
        def myfunc():

            return True

        log(myfunc())

        </script>
    </body>
</html>

        <script type="text/python">
def myfunc():

    return True

log(myfunc())

        </script>

Ordenadores, móvil, navegadores

type=text

Si era posible...

Si, ¡Es posible!

Brython

Galeria