3.8.1 Examples

The following function emulates the default import statement:

import imp
import sys

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

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

    # See if it's a built-in module.
    m = imp.init_builtin(name)
    if m:
        return m

    # See if it's a frozen module.
    m = imp.init_frozen(name)
    if m:
        return m

    # Search the default path (i.e. sys.path).
    fp, pathname, (suffix, mode, type) = imp.find_module(name)

    # See what we got.
    try:
        if type == imp.C_EXTENSION:
            return imp.load_dynamic(name, pathname)
        if type == imp.PY_SOURCE:
            return imp.load_source(name, pathname, fp)
        if type == imp.PY_COMPILED:
            return imp.load_compiled(name, pathname, fp)

        # Shouldn't get here at all.
        raise ImportError, '%s: unknown module type (%d)' % (name, type)
    finally:
        # Since we may exit via an exception, close fp explicitly.
        fp.close()