A tale of two cellphones: Python on Android and iOS

Python is enjoying a surge in popularity due to it's features as a language. However, over the last 10 years, mobile platforms have increased in importance, and Python doesn't have a good story on these platforms.

In this talk, Dr Russell Keith-Magee will give a technical dive into the work the BeeWare project has been doing to make Python as simple to use on Mobile as it is on other platforms.

Video: https://www.youtube.com/watch?v=NqdpK9KjGgQ

Transcript

1. A tale of two cellphones Python on Android and iOS Dr Russell Keith-Magee @freakboy3742 PyCon US 2016
2. A tale of two cellphones Python on Android and iOS Dr Russell Keith-Magee @freakboy3742 PyCon US 2016
5. What is "Mobile Python"?
6. A native application delivered as a native application using native system APIs.
7. A native application...
8. ... delivered as a native application ...
9. ... using native system APIs.
10. What is currently possible?
11. What is currently possible? You can: Write a native iOS application Write a native Android application Write a cross-platform application
12. iOS
13. CPython Issue 23670
14. Using CPython on iOS
15. Python-iOS-template Cookiecutter http://github.com/pybee/Python-iOS-template
16. Accessing native libraries
17. Swift
18. Objective C NSURL *url = [NSURL URLWithString:@"http://pybee.org"];
19. Objective C (intermediate) NSString *str = [ [NSString alloc] initWithCharacters:"http://pybee.org" length:16 ]; NSURL *url = [NSURL URLWithString:str];
20. Objective C in C Class nsstring = objc_getClass("NSString"); SEL alloc = sel_registerName("alloc"); id str = objc_msgsend(nsstring, alloc); SEL init = sel_registerName( "initWithCharacters:length:"); str = objc_msgsend( str, init, "http://pybee.org", 16); Class nsurl = objc_getClass("NSURL"); SEL urlwithstring = sel_registerName( "URLWithString:"); id url = objc_msgsend( nsurl, urlwithstring, str);
21. ctypes from ctypes import * libc = cdll.LoadLibrary("libc.so.6") libc.strchr.argtypes = [c_char_p, c_char] libc.strchr.restype = c_char_p >>> print(libc.strchr(b"abcdef", b"d")) 'def'
22. ctypes and Objective C from ctypes import * lib = util.find_library(b'objc') objc = cdll.LoadLibrary(lib) objc.objc_getClass.argtypes = [c_char_p] objc.objc_getClass.restype = c_void_p NSString = objc.objc_getClass(b'NSString')
23. Descriptors class ObjCInstance: def __getattr__(self, name): print("Getting attribute", name) def __setattr__(self, name, value): print("Set", name, "to", value) >>> obj = ObjCInstance() >>> obj.spam Getting attribute spam >>> obj.pork = "ham" Set attribute pork to ham
24. Callables class Method: def __call__(self, *args) print("Invoke method with args", args) ... >>> method = Method() >>> method(1,2,3) Invoke method with args (1, 2, 3)
25. Object creation class Method: def __new__(cls, *args) ...
26. Rubicon
27. Rubicon from ctypes import cdll, util from rubicon.objc import ObjCClass cdll.LoadLibrary(util.find_library('Foundation')) NSURL = ObjCClass('NSURL'); NSURL.URLWithString_("http://pybee.org/")
28. Rubicon from rubicon.objc import * NSObject = ObjCClass(NSObject) class Handler(NSObject): @objc_method def initWithValue_(self, v: int): self.value = v return self @objc_method def pokeWithValue_(self, v: int) -> None: print ("Poking with", v)
29. An iOS application in Python class PythonAppDelegate(UIResponder): @objc_method def application_didFinishLaunchingWithOptions_( self, application, launchOptions) -> bool: ... class MyViewController(UIViewController): @objc_method def loadView(self) -> None: self.title = 'Add item'
30. Android
31. CPython Issue 23496 https://bitbucket.org/xdegaye/pyona/src
32. Jython
33. Rethinking the problem
34. Inside Python def sing(): for i in range(100, 0, -1): print("%d bottles of beer on the wall" %i) print()
35. Python Bytecode import dis dis.dis(sing)
36. Bytecode 2 0 SETUP_LOOP 47 (to 50) 3 LOAD_GLOBAL 0 (range) 6 LOAD_CONST 1 (100) 9 LOAD_CONST 2 (0) 12 LOAD_CONST 5 (-1) 15 CALL_FUNCTION 3 (3 positional, 0 keyword pair) 18 GET_ITER >> 19 FOR_ITER 27 (to 49) 22 STORE_FAST 0 (i) 3 25 LOAD_GLOBAL 1 (print) 28 LOAD_CONST 4 ('%d bottles of beer on the wall') ...
37. Java package com.example; public class Sing { public static void main(String [] args) { for (int i = 100; i < 0; i--) { System.out.println(i + " bottles of beer on the wall"); } } }
38. Bytecode Max stack: 3 Max locals: 2 Bytecode: (39 bytes) 0: BIPUSH 100 2: ISTORE_1 3: ILOAD_1 4: IFGE 34 7: GETSTATIC java/lang/System.out 10: NEW java/lang/StringBuilder 13: DUP 14: INVOKESPECIAL java/lang/StringBuilder.<init> 17: ILOAD_1 ...
39. VOC
40. An Android application in Python from android.widget import ListView class MainActivity( extends=android.app.Activity): def onCreate(self, state: android.os.Bundle ) -> void: super().onCreate(state) Log.i("MyApp", "Create new app") listview = ListView(self) ...
41. Python-Android-template Cookiecutter http://github.com/pybee/Python-Android-template
42. Cross platform
43. Kivy
44. Toga
45. A Toga App import toga class TodoApp(toga.App): def startup(self): self.list = toga.List( data=[...], on_delete=self.remove_entry, on_refresh=self.refresh ) ...
46. A Toga App (pt II) ... container = toga.NavigationView( title="Todo List", content=self.list, on_action=self.show_add_dialog ) self.main_window.content = container
47. A Toga App (pt III) ... self.input = toga.TextInput(placeholder="thing to do...") self.add_item_dialog = toga.Dialog( title="Add item", content=toga.Container( self.input ), on_accept=self.add_entry ) ...
48. A Toga App (pt IV) def show_add_dialog(self, widget): self.input.clear() self.show_dialog(self.add_item_dialog) def add_entry(self, widget): if self.input.value: self.list.add({'description': self.input.value}) def remove_entry(self, widget): ... def refresh(self, list_widget): ...
49. bit.ly/toga-mobile-demo
50. Packaging
51. pip install briefcase python setup.py ios python setup.py android
52. The future
54. The threat
55. The opportunity
56. It is the best of times, it is the worst of times, it is the age of wisdom, it is the age of foolishness, it is the epoch of belief, it is the epoch of incredulity...
57. Thank you! russell@keith-magee.com @freakboy3742 pybee.org @PyBeeWare Python Mobile-SIG