= Methods of specifying Jython settings =

 * `preProperties`, typically Java system properties specified with `-D` '''before''' class/jar specification on Java command line

 * Registry: property files `registry` in Jython root and `.jython` in `user.home`; if both are present, the latter replaces the former completely.  If either is present, the Java system properties are replaced entirely.  (This is likely a bug in `PySystemState.addRegistryFile`.)  See [[http://www.jython.org/Project/userguide.html#finding-the-registry-file|Finding the Registry File]] for more information.

 * `postProperties`, typically Jython properties specified with `-D` '''after''' class/jar specification on Java command line (these overwrite Java system properties, too.)

For `preProperties` and `postProperties`, alternate properties may be passed to `PySystemState.initialize` or `PythonInterpreter.initialize` by programmatic users of Jython.

The runtime registry (`PySystemState.registry` from Java, or `sys.registry` from Python) is created from the above three sources.

Other command-line arguments are written directly into Options static variables without going through the properties system; the overlapping properties are `python.divisionWarning`, `python.options.Qnew` and `python.verbose`.  In these overlapping cases, the above three sources always take precedence over the command-line equivalents.  (This precedence should likely be reversed.)

== Documentation ==

 * The options whose destinations are static variables in the `Options` class are well-documented [[https://jython.svn.sourceforge.net/svnroot/jython/branches/asm/src/org/python/core/Options.java|there]].

 * The [[https://jython.svn.sourceforge.net/svnroot/jython/branches/asm/registry|default registry file]] is severely bitrotted and needs redoing.

 * The [[http://www.jython.org/Project/userguide.html#the-jython-registry|Jython user guide]] refers to a subset of these properties.

|| Source                                       || Destination                         || Default                             ||
|| install.root                                 ||                                     ||                                     ||
|| python.cachedir                              || PySystemState.cachedir = File(...)  || "cachedir"                          ||
|| python.cachedir.skip                         || PySystemState.cachedir = null       || true if standalone, else false      ||
|| python.collections                           || PyInstance.initializeIterators      || ""                                  ||
|| python.console                               || jython.main                         || "org.python.util.InteractiveConsole"||
|| python.console.encoding                      || CompilerFlags.encoding              ||                                     ||
|| python.console.readlinelib                   ||                                     ||                                     ||
|| python.deprecated.keywordMangling            || Options.deprecatedKeywordMangling   || false                               ||
|| python.divisionWarning                       || Options.divisionWarning             ||                                     ||
|| python.executable                            || PySystemState.[default]Executable   || set by launcher script, else null   ||
|| python.home                                  || PySystemState.[exec_]prefix         || set by launcher script, else "."    ||
|| python.modules.builtin                       || PySystemState.builtin_module_names  || ""; appended to Setup.builtinModules||
|| python.options.Qnew                          || Options.Qnew                        || false                               ||
|| python.options.caseok                        || Options.caseok                      || false                               ||
|| python.options.compileClass                  || ''unused; in default registry file''|| false (in registry file)            ||
|| python.options.includeJavaStackInExceptions  || Options.includeJavaStackInExceptions|| true                               ||
|| python.options.internalTablesImpl            || InternalTables.createInternalTables || null                                ||
|| python.options.proxyDebugDirectory           || Options.proxyDebugDirectory         || null                                ||
|| python.options.showJavaExceptions            || Options.showJavaExceptions          || false                               ||
|| python.options.showPythonProxyExceptions     || Options.showPythonProxyExceptions   || false                               ||
|| python.os                                    || os._name                            || "posix"                             ||
|| python.packages.directories                  || SysPackageManager.findAllPackages   || "java.ext.dirs" (see PackageScanning)||
|| python.packages.fakepath                     || SysPackageManager.findAllPackages   || null                                ||
|| python.packages.paths                        || SysPackageManager.findAllPackages   || "java.class.path,sun.boot.class.path"||
|| python.path {X}                              || end of path after JYTHON_JAR/Lib    || ""                                  ||
|| python.prepath (python.path in r5043+)       || beginning of path after current dir || ""                                  ||
|| python.security.respectJavaAccessibility     || Options.respectJavaAccessibility    || true                                ||
|| python.verbose                               || Options.verbose                     || Py.MESSAGE = 1                      ||
|| python.xml.sax.parser                        || xml.sax.default_parser_list (split) || PY_SAX_PARSER, else xml.sax.drivers2.drv_javasax ||

{X} gone in Jython 2.5 or later