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"""Alternative to reload().
This works by executing the module in a scratch namespace, and then
patching classes, methods and functions. This avoids the need to
patch instances. New objects are copied into the target namespace.
"""
import imp
import sys
import types
def xreload(mod):
"""Reload a module in place, updating classes, methods and functions.
Args:
mod: a module object
Returns:
The (updated) input object itself.
"""
# Get the module name, e.g. 'foo.bar.whatever'
modname = mod.__name__
# Get the module namespace (dict) early; this is part of the type check
modns = mod.__dict__
# Parse it into package name and module name, e.g. 'foo.bar' and 'whatever'
i = modname.rfind(".")
if i >= 0:
pkgname, modname = modname[:i], modname[i+1:]
else:
pkgname = None
# Compute the search path
if pkgname:
# We're not reloading the package, only the module in it
pkg = sys.modules[pkgname]
path = pkg.__path__ # Search inside the package
else:
# Search the top-level module path
pkg = None
path = None # Make find_module() uses the default search path
# Find the module; may raise ImportError
(stream, filename, (suffix, mode, kind)) = imp.find_module(modname, path)
# Turn it into a code object
try:
# Is it Python source code or byte code read from a file?
# XXX Could handle frozen modules, zip-import modules
if kind not in (imp.PY_COMPILED, imp.PY_SOURCE):
# Fall back to built-in reload()
return reload(mod)
if kind == imp.PY_SOURCE:
source = stream.read()
code = compile(source, filename, "exec")
else:
code = marshal.load(stream)
finally:
if stream:
stream.close()
# Execute the code. We copy the module dict to a temporary; then
# clear the module dict; then execute the new code in the module
# dict; then swap things back and around. This trick (due to
# Glyph Lefkowitz) ensures that the (readonly) __globals__
# attribute of methods and functions is set to the correct dict
# object.
tmpns = modns.copy()
modns.clear()
modns["__name__"] = tmpns["__name__"]
exec(code, modns)
# Now we get to the hard part
oldnames = set(tmpns)
newnames = set(modns)
# Update attributes in place
for name in oldnames & newnames:
modns[name] = _update(tmpns[name], modns[name])
# Done!
return mod
def _update(oldobj, newobj):
"""Update oldobj, if possible in place, with newobj.
If oldobj is immutable, this simply returns newobj.
Args:
oldobj: the object to be updated
newobj: the object used as the source for the update
Returns:
either oldobj, updated in place, or newobj.
"""
if oldobj is newobj:
# Probably something imported
return newobj
if type(oldobj) is not type(newobj):
# Cop-out: if the type changed, give up
return newobj
if hasattr(newobj, "__reload_update__"):
# Provide a hook for updating
return newobj.__reload_update__(oldobj)
if isinstance(newobj, types.ClassType):
return _update_class(oldobj, newobj)
if isinstance(newobj, types.FunctionType):
return _update_function(oldobj, newobj)
if isinstance(newobj, types.MethodType):
return _update_method(oldobj, newobj)
if isinstance(newobj, classmethod):
return _update_classmethod(oldobj, newobj)
if isinstance(newobj, staticmethod):
return _update_staticmethod(oldobj, newobj)
# XXX How to support decorators?
# Not something we recognize, just give up
return newobj
# All of the following functions have the same signature as _update()
def _update_function(oldfunc, newfunc):
"""Update a function object."""
oldfunc.__doc__ = newfunc.__doc__
oldfunc.__dict__.update(newfunc.__dict__)
oldfunc.__code__ = newfunc.__code__
oldfunc.__defaults__ = newfunc.__defaults__
# XXX What else?
return oldfunc
def _update_method(oldmeth, newmeth):
"""Update a method object."""
# XXX What if im_func is not a function?
_update(oldmeth.im_func, newmeth.im_func)
return oldmeth
def _update_class(oldclass, newclass):
"""Update a class object."""
# XXX What about __slots__?
olddict = oldclass.__dict__
newdict = newclass.__dict__
oldnames = set(olddict)
newnames = set(newdict)
for name in newnames - oldnames:
setattr(oldclass, name, newdict[name])
for name in oldnames - newnames:
delattr(oldclass, name)
for name in oldnames & newnames - {"__dict__", "__doc__"}:
setattr(oldclass, name, _update(olddict[name], newdict[name]))
return oldclass
def _update_classmethod(oldcm, newcm):
"""Update a classmethod update."""
# While we can't modify the classmethod object itself (it has no
# mutable attributes), we *can* extract the underlying function
# (by calling __get__(), which returns a method object) and update
# it in-place. We don't have the class available to pass to
# __get__() but any object except None will do.
_update(oldcm.__get__(0), newcm.__get__(0))
return newcm
def _update_staticmethod(oldsm, newsm):
"""Update a staticmethod update."""
# While we can't modify the staticmethod object itself (it has no
# mutable attributes), we *can* extract the underlying function
# (by calling __get__(), which returns it) and update it in-place.
# We don't have the class available to pass to __get__() but any
# object except None will do.
_update(oldsm.__get__(0), newsm.__get__(0))
return newsm
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