Python in a Nutshell, 2nd Edition

Compiling Python into Java

Jython comes with the jythonc compiler. You can feed jythonc your .py source files, and jythonc compiles them into normal JVM bytecode and packages them into .class and .jar files. Since jythonc generates traditional static bytecode, it cannot quite cope with the whole range of dynamic possibilities that Python allows. For example, jythonc cannot successfully compile Python classes that determine their base classes dynamically at runtime, as the normal Python interpreters allow. However, except for such extreme examples of dynamically changeable class structures, jythonc does support compilation of essentially the whole Python language into Java bytecode.

The jythonc Command

jythonc resides in the Tools/jythonc directory of your Jython installation. You invoke it from a shell (console) command line with the syntax:

jythonc options modules

options are zero or more option flags starting with --. modules are zero or more names of Python source files to compile, either as Python-style names of modules residing on Python’s sys.path, or as relative or absolute paths to Python source files. Include the .py extension in each path to a source file, but not in a module name.

More often than not, you will specify the jythonc option --jar jarfile to build a .jar file of compiled bytecode rather than separate .class files. Most other options deal with what to put in the .jar file. You can choose to make the file self-sufficient (for browsers and other Java runtime environments ...