The following function emulates what was the standard import statement up to Python 1.4 (i.e., 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 standard module knee (which is intended as an example only -- don't rely on any part of it being a standard interface).