ref: 5513dae7d9eee46f7e1843c8eeeaf9066d0ec632
dir: /sys/src/cmd/python/Demo/imputil/knee.py/
"""An Python re-implementation of hierarchical module import.
This code is intended to be read, not executed. However, it does work
-- all you need to do to enable it is "import knee".
(The name is a pun on the klunkier predecessor of this module, "ni".)
"""
import sys, imp, __builtin__
# Replacement for __import__()
def import_hook(name, globals=None, locals=None, fromlist=None):
parent = determine_parent(globals)
q, tail = find_head_package(parent, name)
m = load_tail(q, tail)
if not fromlist:
return q
if hasattr(m, "__path__"):
ensure_fromlist(m, fromlist)
return m
def determine_parent(globals):
if not globals or not globals.has_key("__name__"):
return None
pname = globals['__name__']
if globals.has_key("__path__"):
parent = sys.modules[pname]
assert globals is parent.__dict__
return parent
if '.' in pname:
i = pname.rfind('.')
pname = pname[:i]
parent = sys.modules[pname]
assert parent.__name__ == pname
return parent
return None
def find_head_package(parent, name):
if '.' in name:
i = name.find('.')
head = name[:i]
tail = name[i+1:]
else:
head = name
tail = ""
if parent:
qname = "%s.%s" % (parent.__name__, head)
else:
qname = head
q = import_module(head, qname, parent)
if q: return q, tail
if parent:
qname = head
parent = None
q = import_module(head, qname, parent)
if q: return q, tail
raise ImportError, "No module named " + qname
def load_tail(q, tail):
m = q
while tail:
i = tail.find('.')
if i < 0: i = len(tail)
head, tail = tail[:i], tail[i+1:]
mname = "%s.%s" % (m.__name__, head)
m = import_module(head, mname, m)
if not m:
raise ImportError, "No module named " + mname
return m
def ensure_fromlist(m, fromlist, recursive=0):
for sub in fromlist:
if sub == "*":
if not recursive:
try:
all = m.__all__
except AttributeError:
pass
else:
ensure_fromlist(m, all, 1)
continue
if sub != "*" and not hasattr(m, sub):
subname = "%s.%s" % (m.__name__, sub)
submod = import_module(sub, subname, m)
if not submod:
raise ImportError, "No module named " + subname
def import_module(partname, fqname, parent):
try:
return sys.modules[fqname]
except KeyError:
pass
try:
fp, pathname, stuff = imp.find_module(partname,
parent and parent.__path__)
except ImportError:
return None
try:
m = imp.load_module(fqname, fp, pathname, stuff)
finally:
if fp: fp.close()
if parent:
setattr(parent, partname, m)
return m
# Replacement for reload()
def reload_hook(module):
name = module.__name__
if '.' not in name:
return import_module(name, name, None)
i = name.rfind('.')
pname = name[:i]
parent = sys.modules[pname]
return import_module(name[i+1:], name, parent)
# Save the original hooks
original_import = __builtin__.__import__
original_reload = __builtin__.reload
# Now install our hooks
__builtin__.__import__ = import_hook
__builtin__.reload = reload_hook