WxPython: PyInstaller fails with No module named _core_

Question

I am converting my wxpython (3.0.2.0) application to binaries using PyInstaller. The binaries work fine when built and executed on Ubuntu 12.04. However if I build on Ubuntu

Answer 1

If PyInstaller development version is not desired for some reason, here goes some fix.

Instance ofBuiltinImporter, FrozenImporter and CExtensionImporter from PyInstaller.loader.pyi_importers are appended to sys.meta_path. And find_module method of which are called in order until one of them succeeds when a module is imported.

CExtensionImporter chooses only one of the many suffixes for the C extension to load, f.e. wx._core_.i386-linux-gnu.so. That's why it fails to load the C extension wx._core_.so.

Buggy code;

class CExtensionImporter(object):
    def __init__(self):
        # Find the platform specific suffix. On Windows it is .pyd, on Linux/Unix .so.
        for ext, mode, typ in imp.get_suffixes():
            if typ == imp.C_EXTENSION:
                self._c_ext_tuple = (ext, mode, typ)
                self._suffix = ext  # Just string like .pyd  or  .so
                break

Fix;

1. Runtime hooks
It's possible to fix the problem without code change using runtime hooks. This is a quick fix which fixes 'WxPython' problems.
This runtime hook changes some private attributes of instance of CExtensionImporter. To use this hook, give --runtime-hook=wx-run-hook.py to pyinstaller.

wx-run-hook.py

import sys
import imp

sys.meta_path[-1]._c_ext_tuple = imp.get_suffixes()[1]
sys.meta_path[-1]._suffix = sys.meta_path[-1]._c_ext_tuple[0]

This second runtime hook completely replaces object in sys.meta_path[-1]. So it should work in most situations. Use as pyinstaller --runtime-hook=pyinstaller-run-hook.py application.py.

pyinstaller-run-hook.py

import sys
import imp

from PyInstaller.loader import pyi_os_path

class CExtensionImporter(object):
    """
    PEP-302 hook for sys.meta_path to load Python C extension modules.

    C extension modules are present on the sys.prefix as filenames:

        full.module.name.pyd
        full.module.name.so
    """
    def __init__(self):
        # TODO cache directory content for faster module lookup without file system access.
        # Find the platform specific suffix. On Windows it is .pyd, on Linux/Unix .so.
        self._c_ext_tuples = [(ext, mode, typ) for ext, mode, typ in imp.get_suffixes() if typ == imp.C_EXTENSION]

        # Create hashmap of directory content for better performance.
        files = pyi_os_path.os_listdir(sys.prefix)
        self._file_cache = set(files)

    def find_module(self, fullname, path=None):
        imp.acquire_lock()
        module_loader = None  # None means - no module found by this importer.

        # Look in the file list of sys.prefix path (alias PYTHONHOME).
        for ext, mode, typ in self._c_ext_tuples:
            if fullname + ext in self._file_cache:
                module_loader = self
                self._suffix = ext
                self._c_ext_tuple = (ext, mode, typ)
                break

        imp.release_lock()
        return module_loader

    def load_module(self, fullname, path=None):
        imp.acquire_lock()

        try:
            # PEP302 If there is an existing module object named 'fullname'
            # in sys.modules, the loader must use that existing module.
            module = sys.modules.get(fullname)

            if module is None:
                filename = pyi_os_path.os_path_join(sys.prefix, fullname + self._suffix)
                fp = open(filename, 'rb')
                module = imp.load_module(fullname, fp, filename, self._c_ext_tuple)
                # Set __file__ attribute.
                if hasattr(module, '__setattr__'):
                    module.__file__ = filename
                else:
                    # Some modules (eg: Python for .NET) have no __setattr__
                    # and dict entry have to be set.
                    module.__dict__['__file__'] = filename

        except Exception:
            # Remove 'fullname' from sys.modules if it was appended there.
            if fullname in sys.modules:
                sys.modules.pop(fullname)
            # Release the interpreter's import lock.
            imp.release_lock()
            raise  # Raise the same exception again.

        # Release the interpreter's import lock.
        imp.release_lock()

        return module

    ### Optional Extensions to the PEP302 Importer Protocol

    def is_package(self, fullname):
        """
        Return always False since C extension modules are never packages.
        """
        return False

    def get_code(self, fullname):
        """
        Return None for a C extension module.
        """
        if fullname + self._suffix in self._file_cache:
            return None
        else:
            # ImportError should be raised if module not found.
            raise ImportError('No module named ' + fullname)

    def get_source(self, fullname):
        """
        Return None for a C extension module.
        """
        if fullname + self._suffix in self._file_cache:
            return None
        else:
            # ImportError should be raised if module not found.
            raise ImportError('No module named ' + fullname)

    def get_data(self, path):
        """
        This returns the data as a string, or raise IOError if the "file"
        wasn't found. The data is always returned as if "binary" mode was used.

        The 'path' argument is a path that can be constructed by munging
        module.__file__ (or pkg.__path__ items)
        """
        # Since __file__ attribute works properly just try to open and read it.
        fp = open(path, 'rb')
        content = fp.read()
        fp.close()
        return content

    # TODO Do we really need to implement this method?
    def get_filename(self, fullname):
        """
        This method should return the value that __file__ would be set to
        if the named module was loaded. If the module is not found, then
        ImportError should be raised.
        """
        if fullname + self._suffix in self._file_cache:
            return pyi_os_path.os_path_join(sys.prefix, fullname + self._suffix)
        else:
            # ImportError should be raised if module not found.
            raise ImportError('No module named ' + fullname)

#This may overwrite some other object
#sys.meta_path[-1] = CExtensionImporter()

#isinstance(object, CExtensionImporter)
#type(object) == CExtensioImporter
#the above two doesn't work here

#grab the index of instance of CExtensionImporter

for i, obj in enumerate(sys.meta_path):
    if obj.__class__.__name__ == CExtensionImporter.__name__:
        sys.meta_path[i] = CExtensionImporter()
        break

2. Code change

class CExtensionImporter(object):
    def __init__(self):
        # Find the platform specific suffix. On Windows it is .pyd, on Linux/Unix .so.
        self._c_ext_tuples = [(ext, mode, typ) for ext, mode, typ in imp.get_suffixes() if typ == imp.C_EXTENSION]

        files = pyi_os_path.os_listdir(sys.prefix)
        self._file_cache = set(files)

Because imp.get_suffixes returns more than one suffixes for type imp.C_EXTENSION and the right one can't be known in advance until a module is found, I store all of them in a list self._c_ext_tuples. The right suffix is set in self._suffix, which is used along with self._c_ext_tuple by load_module method, from find_module method if the module is found.

def find_module(self, fullname, path=None):
    imp.acquire_lock()
    module_loader = None  # None means - no module found by this importer.

    # Look in the file list of sys.prefix path (alias PYTHONHOME).
    for ext, mode, typ in self._c_ext_tuples:
        if fullname + ext in self._file_cache:
            module_loader = self
            self._suffix = ext
            self._c_ext_tuple = (ext, mode, typ)
            break

    imp.release_lock()
    return module_loader

Answer 2

Fundamentally the problem is with the PyInstaller version - you need to be on the develop version. This issue has been seen and is documented on a PyInstaller Github issue.

To install the latest version and rectify - at the command prompt type:

$ pip install git+https://github.com/pyinstaller/pyinstaller

This directly installs the latest version of pyinstaller from github (this branch on github. Until recently, PyInstaller had a separate python3 branch, but this has been merged back into the develop branch. If you need to use Python 3.x, you will need this branch - get this by appending @develop to the pip install command)

The above method relies on you having git installed on your system to get the pyinstaller code (pretty likely for a developer these days, I guess). If not, you can either

1. install git using apt-get install git (you might need to sudo that)
2. download the pyinstaller-develop zip file (here) and install manually. Note as per the wiki as of Oct 2014, this should support 2.7 and 3.x.

Personally - I much prefer option 1 as you avoid all the potential problems of building from a zipped source tree yourself.

Testing

I tested this on Ubuntu 14.04, 64 bit, wxpython 3.0.2.0 with python 2.7.6, using the simple "Hello world" app from the wxPython webpage. The OP's issue reproduced exactly before installing pyinstaller develop version. After installing the develop version the app built correctly and ran as an executable.

---

Documentation of using pip with git - https://pip.pypa.io/en/latest/reference/pip_install.html#git

It is not clear from your question which versions of PyInstaller you are using on your Ubuntu 12.04 install vs the 14.04 version. It seems that the version you have on 12.04 does not exhibit the same issue as the standard version installed on 14.04.