Testing black magic

pythonize.py

# ↓↓↓ Scroll to bottom for an example. ↓↓↓

import importlib
import pkgutil


def pythonize(qt_package):
    proxy = _PackageProxy(qt_package)
    return proxy


def _make_class_proxy(qt_klass):

    class ClassProxy(object):

        def __init__(self, *args, **kwargs):
            super(ClassProxy, self).__init__()
            self.__backend = qt_klass(*args, **kwargs)

        def __getattr__(self, name):
            # Convert Pythonic attribute names to camel case names.
            if name[0].islower():
                # this_is_an_attribute => thisIsAnAttribute
                comps = name.split('_')
                comps = comps[:1] + [c.title() for c in comps[1:]]
            else:
                # THIS_IS_A_CONSTANT => ThisIsAConstant
                comps = [c.title() for c in name.split('_')]
            name = ''.join(comps)
            return getattr(self.__backend, name)

    return ClassProxy


class _ModuleProxy(object):

    def __init__(self, module):
        super(_ModuleProxy, self).__init__()
        self.module = module

    def __getattr__(self, name):
        try:
            qt_klass = getattr(self.module, name)
        except AttributeError:
            qt_klass = getattr(self.module, 'Q' + name)
        proxy = _make_class_proxy(qt_klass)
        return proxy


class _PackageProxy(object):

    def __init__(self, package):
        prefix = package.__name__ + '.'
        path = package.__path__
        for _, full_name, _ in pkgutil.iter_modules(path, prefix):
            name = full_name.split('.')[-1]
            if name.startswith('Qt'):
                # Modules like QtCore, QtGui, QtWidgets, etc.
                # Strip "Qt" prefix, convert to lower (i.e. core, gui, widgets)
                # Note that multiword modules won't contain underscores. For
                # example "QtPrintSupport" will become "printsupport".
                local_name = name[2:].lower()
            elif name[0].isupper():
                # Modules without the "Qt" prefix (e.g. Enginio)
                local_name = name.lower()
            elif name[0] == '_':
                # Private module. Skip.
                continue
            else:
                # Normal packages. Use as-is.
                local_name = name
            module = importlib.import_module(full_name)
            proxy = _ModuleProxy(module)
            # Inject this into the local scope.
            setattr(self, local_name, proxy)


# I'm testing with PyQt5. Rewrite where appropriate.
import sys
import PyQt5
qt = pythonize(PyQt5)
app = qt.widgets.Application(sys.argv)
w = qt.widgets.MainWindow()
w.show()
app.exec_()

todo.md

• Use metaclass instead of class wrapper to avoid breaking the inheritance chain.
• Map global functions and macros (e.g. qApp, QT_VERSION, etc.)
• Special-case things in the Qt global namespace (PyQt5.Qt). There are a lot of things in it, including aliases to all public classes and constants.
• Python-specific things like pyqtSignal (and similar things in PySide).