Python for Series 60

Transcript Python for Series 60

Python for Series 60 (i.e. Python on a Phone)

Jukka Laurila EuroPython 2005 1 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

What is Series 60?

• • • • • • • • • • 100-220 MHz ARM processor (and a separate processor for telephony functions) Typically 4 – 8 MB of free RAM FAT formatted Flash as mass storage Symbian OS Series 60 software for UI, comms, applications etc.

GSM, GPRS, UMTS, Bluetooth, IrDA, WLAN...

Display: 176x208 12-18 bpp LCD panel (currently, N90 has 352x416) Integrated camera (usually) 20 million shipped by Nokia alone In other words: A pretty capable computer • ...with an always-on Internet connection • ...that’s with you all the time • • ...that you can write your own software for ...IF you spend enough effort 2 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Why port Python to a phone?

• • • • • • • • • • Symbian C++ development is slow and hard Java has limited access to platform capabilities Easy to learn, clear syntax High productivity (See: Lutz Prechelt:

An empirical comparison of seven programming languages

, IEEE Computer 33(10):23-29, October 2000) Extending and embedding easy and efficient Popular Good standard library Reasonable memory footprint Ports to other “embedded” systems already existed at the time (PalmOS) Other choices: • ECMAScript • Perl (actually we did port Perl, too) 3 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Past and Future

• • • • • Stable 1.0 release Dec 2004 1.1.x pre-alpha series releases ongoing, soliciting feedback from external developers • We need you!

Stable 1.2 release coming later this year A standard component in future phones? Maybe.

Source release? Working on it...

4 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Python for Series 60 1.1.5

• • • Python 2.2.2 as a Symbian DLL Extensible and embeddable with the Python/C API Standard library • socket (TCP/IP, SSL, Bluetooth serial connections), urllib, httplib, nntplib, thread, math, re, sre, marshal, anydbm, whichdbm etc...

• • File system access Many modules written in Python work unchanged or with minor changes • C modules need to be modified 5 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Bindings to Series 60 API’s

• • • • • • appuifw: a simple S60 UI API SMS sending Native Symbian SQL database (e32db module), dbm (over e32db) Location API (Cell ID) Background “daemon” process support New in 1.1 series: • 2D graphics • Binding to Symbian GDI graphics • API partly similar to PIL • • Image loading, saving, scaling, rotation, bitblit Set of graphics primitives • • • • Raw key event handling camera contacts calendar • • • • telephony audio: record and play samples, MIDI sysinfo miscellaneous improvements, like rich text support 6 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

appuifw

• • • Our own API for Series 60 GUI programming S60 UI made as simple as possible Just one widget allowed on screen at a time

import appuifw appuifw.note(u’Hello World!’)

Form Listbox & Tabs Text widget Content handler Popup menu Multifield query 7 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Porting difficulties…

• • • • • • No global writable data allowed in DLL’s • Globals moved to heap-allocated struct referenced via TLS No standard C++ exceptions • Instead TRAP/Leave (think setjmp/longjmp), Cleanup Stack Memory and disk space constraints • We can run out of memory at any time and should survive it C stdlib not quite complete • Locale-specific float formatting: 3.14 vs. 3,14 Symbian and S60 API complexity Active Objects: co-op multitasking and event handling the Symbian way 8 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Co-op multitasking and event handling the Symbian way

Active Object: object that inherits from CActive, has a RunL method   think “event handler” or “co-operative task” Active Scheduler: a loop that runs RunL methods of AO’s in sequence think “event loop” or “co-operative multitasking engine” Thread AO RunL() { ...run code... run nested AS ...run more code... } AS AO RunL() { ...refresh UI widget... } AO RunL() { ...put data received from a socket to a buffer...} lock=e32.Ao_lock() lock.wait() start a nested AS and run until the lock is .signal()ed e32.ao_yield() start a nested AS and run through it

once

Remaining problems

• • • • • unicode vs. str ugliness:

appuifw.note(u’foo’) appuifw.popup_menu([u’first’,u’second],u’Pick one:’)

Very little performance optimizations have been done yet, so there’s a lot of room for improvement • • Slow imports Globals access using Thread Local Storage is a real killer Native Symbian resources aren’t threadsafe… at all. No gc support yet • • Unfreed native resources cause an error message on exit …which is nasty since reference cycles are easy to make Creating C extensions on Symbian is not as easy as it should be • Manual work required, no distutils, SWIG, SIP or any of that magic (yet) 10 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila

Demos!

Questions?

For more information: http://www.forum.nokia.com/ http://discussion.forum.nokia.com/ 12 © NOKIA EuroPython_PythonForSeries60.PPT / 2005-06-27 / Jukka Laurila