3.21.1 Examples

##
3.21.1 Examples

The following function emulates what was the standard import statement up to Python 1.4 (no hierarchical module names). (This implementation wouldn't work in that version, since `find_module()` has been extended and `load_module()` has been added in 1.4.)

    import imp
    import sys

    def __import__(name, globals=None, locals=None, fromlist=None):
        # Fast path: see if the module has already been imported.
        try:
            return sys.modules[name]
        except KeyError:
            pass

        # If any of the following calls raises an exception,
        # there's a problem we can't handle -- let the caller handle it.

        fp, pathname, description = imp.find_module(name)

        try:
            return imp.load_module(name, fp, pathname, description)
        finally:
            # Since we may exit via an exception, close fp explicitly.
            if fp:
                fp.close()

A more complete example that implements hierarchical module names and includes a `reload()` function can be found in the module `knee`. The `knee` module can be found in Demo/imputil/ in the Python source distribution.