FAQ

Does Jep work on Android?

• We haven't tried it yet. In theory it should possible, but there may be some challenges to overcome. If you try this, we'd love to hear about it and will gladly accept contributions to make Jep work well on more platforms.

What Python modules does Jep work with?

• Jep should work with any pure python modules. Unfortunately, CPython extensions and Cython modules may not work correctly, it depends on how they were coded. We have started a list of Package Compatibility. Please contribute to the list with your findings.

What Java UI frameworks does Jep support?

• Jep has been run with Swing and SWT. We haven't tried JavaFX yet, but it should work.

What's the typical usage of Jep code look like?

try(Jep jep = new Jep(false)) {
    jep.eval("import somePyModule");
    // any of the following work, these are just pseudo-examples

    // using eval(String) to invoke methods
    jep.setValue("arg", obj);
    jep.eval("x = somePyModule.foo1(arg)");
    Object result1 = jep.getValue("x");

    // using getValue(String) to invoke methods
    Object result2 = jep.getValue("somePyModule.foo2()");

    // using invoke to invoke methods
    Object result3 = jep.invoke("somePyModule.foo3", obj);

   // using runScript
   jep.runScript("path/To/Script");
}

Why does eval(String) return a boolean instead of an Object of the result?

• eval(String) was originally written to support interactive mode or non-interactive mode (multiple statements or a single statement, see javadoc), so the boolean return value is whether or not the statement was actually executed. There is also an overhead of always returning the result, especially if code is making multiple calls to eval(String) and doesn't need the results. To change the method signature now would potentially break compatibility with a number of applications.
• getValue(String) is almost identical in the C code to eval(String) and will return the result of the evaluation, and can be used instead of eval where desired. For example:

    // evaluates and discards the result
    jep.eval("2 + 4");

    // evaluates and places the results in x
    jep.eval("x = 2 + 4");
    Integer x = (Integer) jep.getValue("x");

    // evaluates and returns the results
    Integer y = (Integer) jep.getValue("2 + 4");