Is there any particular reason to translate the python code to Java? Couldn't that step be omitted by making a python to Dalvik bytecode compiler?
On Thu, Sep 1, 2011 at 6:17 PM, Kristopher Micinski <[email protected]> wrote: > On Thu, Sep 1, 2011 at 12:08 PM, eukreign <[email protected]> wrote: >> Hello, >> >> I've spent a few evenings working on a project to be able to write >> Android applications in Python by compiling Python source into Java >> source. I thought I'd share what I have in case there is interest in >> this (maybe even outside of Android development). I see this project >> having two parts, a Python to Java converter and a very basic >> simulated/stubbed out Java/Android API (so that one could write unit >> tests in python and run them in python, before compiling everything >> into Java). >> >> Of course 100% Python to Java is not possible or practical to >> implement in a reasonable amount of time but I think enough could be >> implemented so that we could have 100% Python syntax with maybe 50% >> Python semantics and 50% Java semantics. I think just getting to that >> point would be a huge productivity gain on working with any java >> frameworks/APIs. Over time I think there can be work arounds for >> things that Java can't do like multiple inheritance, dynamic class >> creation, duck typing, etc. >> >> So, how does it work? I use Pythons ast and symtable modules to walk >> the source code and try to infer the possible types that a variable >> can have. This gives me the type information that Java will need. Then >> another pass generates Java source using this type information. There >> is nothing particularly magical especially since duck typing isn't >> implemented and you can't change the type of a variable after you've >> assigned to it the first time. So you have to be very careful with the >> Python code you write, think of it as statically typed Python where >> you don't have to declare types since they are inferred. I haven't >> gotten to lists and dictionaries yet but the principles will be the >> same, you can't have heterogeneous lists so the first thing you put in >> a list will provide that lists type. >> >> Why not use PyPy? It's possible to achieve some of my goals with >> PyPy and in some cases it will achieve a lot more than I will ever >> attempt to implement. One advantage of PyPy is that it supports a lot >> more of Pythons dynamism (for one, PyPy generates code from a loaded >> Python module while py2j uses static python source files). There are >> two major problems with PyPy for my purposes: 1) it generates >> specialized jvm byte code that the dalvik vm cannot convert 2) because >> PyPy is more pythonic it will be much harder to compile code in a way >> that will just plugin into the Android APIs, with PyPy you can't >> import Java packages or inherit from Java classes as you would have to >> do to write Android apps. >> >> Code I have so far is hosted here: https://bitbucket.org/eukreign/py2j/src >> >> I would say it's still more of a prototype than even alpha level >> code. You can see an example of input file and output in the samples >> directory. >> >> Also, the bottom of both analyze.py and compiler.py have a ton of >> unit tests you can look at to see what is possible so far. >> >> If you have questions or are interested in helping me please send me >> an email. >> >> - lex >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Android Developers" group. >> To post to this group, send email to [email protected] >> To unsubscribe from this group, send email to >> [email protected] >> For more options, visit this group at >> http://groups.google.com/group/android-developers?hl=en > > Lex, > > Sounds like a fun hobby project, but also a lot of work if you > *actually* want it to work well ;-). If you want to just get a quick > and dirty solution, perhaps you should look here: > > http://code.google.com/p/android-scripting/ > > Neat idea otherwise, though. > > Kris > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- Michael Banzon http://michaelbanzon.com/ -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
