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I'm planning to create XULRunner based application that need to interface with Python. The plan is to use PyXPCOM. Currently I'm teaching myself in using PyXPCOM and going through the example component developmnet in Creating a Python XPCOM component but can't get it to work.

I'm using Ubuntu 11.04 and my steps were:

  1. Created an application directory and copied my XULRUnner 5.x binary distribution into it the xulrunner subdirectory

  2. Successfully built PyXPCOM following Building PyXPCOM

  3. Followed the installation instructions in the PyXPCOM source README.txt file and copied the whole content of the directory obj/dist/bin into my xulrunner subdirectory and added the below line in the xulrunner/chrome.manifest file:

    manifest components/pyxpcom.manifest

  4. Created the nsIPySimple.idl file and placed it in my application components subdirectory:

    #include "nsISupports.idl"
[scriptable, uuid(2b324e9d-a322-44a7-bd6e-0d8c83d94883)]
interface nsIPySimple : nsISupports {
    attribute string yourName;
    void write( );
    void change(in string aValue);
};

  5. Created the xpt file by executing the below command in my components subdirectory:

    [xul-sdk-path]/xpidl -m typelib -w -v -I [xul-sdk-path]/idl/ nsIPySimple.idl

  6. Created the nsIPySimple.py in my components subdirectory

    from xpcom import components, verbose

class PySimple: #PythonTestComponent
    _com_interfaces_ = components.interfaces.nsIPySimple
    _reg_clsid_ = "{607ebc50-b8ba-11e0-81d9-001cc4c794e3}"
    _reg_contractid_ = "@mozilla.org/PySimple;1"

    def __init__(self):
        self.yourName = "a default name" # or mName ?

    def __del__(self):
        if verbose:
            print "PySimple: __del__ method called - object is destructing"

    def write(self):
        print self.yourName

    def change(self, newName):
        self.yourName = newName

PYXPCOM_CLASSES = [
    PySimple,
]

  7. Registered the python code by adding the following lines in my chrome.manifest file:

    interfaces  components/nsIPySimple.xpt
component   {607ebc50-b8ba-11e0-81d9-001cc4c794e3} components/nsIPySimple.py
contract    @mozilla.org/PySimple;1 {607ebc50-b8ba-11e0-81d9-001cc4c794e3}

  8. Created the Javascript function to call the Python method:

    function showMore() {
    try {
        testComp = Components.classes["@mozilla.org/PySimple;1"].name;
        alert(testComp);
        testComp = Components.classes["@mozilla.org/PySimple;1"].
                       createInstance(Components.interfaces.nsIPySimple);

        testComp.write();
    }
    catch (anError) {
        alert(anError);
    }
}

But the Javascript code throws the following exception:

[Exception... "Component returned failure code: 0x80570015 
(NS_ERROR_XPC_CI_RETURNED_FAILURE) [nsIJSCID.createInstance]"  
nsresult: "0x80570015 (NS_ERROR_XPC_CI_RETURNED_FAILURE)"  
location: "JS frame :: chrome://reader/content/main.js :: 
showMore :: line 5"  data: no]

Any idea what happened or what I did wrong?

Thanks for the help and clarification!

rahmad
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1 Answers1

1

The error message indicates that createInstance() call resulted in an error. The good news: this means that everything preceding createInstance() succeeded (PyXPCOM is working and the component was loaded/registered correctly). http://code.google.com/p/pythonext/source/browse/samples/pyshell/components/pyShell.py indicates that _com_interfaces_ needs to be a list so maybe that's the problem here. If the supported interfaces aren't specified correctly then it makes sense that creating an instance fails.

Wladimir Palant
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  • It still throws the same exception. But after working it out with the good people @ ActiveState I found out that the problem was with xulrunner-stub. When I ran my application using the stub it throws the exception but if I ran it directly with xulrunner everything works! – rahmad Aug 12 '11 at 05:39
  • But thanks for pointing this out, I didn't notice it was a list. Maybe because of the automatic color coding on the site. The [] was not clear enough for me to see until you pointed it out. – rahmad Aug 12 '11 at 05:43
  • Finally figured out why the xulrunner-stub was throwing an exception why xulrunner itself didn't. The xulrunner-stub was not loading the needed library: libxpcom.so and libpyxpcom.so. When I listed thee two files in the dependentlibs.list file both xulrunner-stub and xulrunner worked as expected. – rahmad Aug 27 '11 at 17:18