# In tools/, make a subdirectory _stable_1_0_2 containing the 1.0.2 stable
# version of the "tools" package. Make _stable_1_0 and _stable_1 symlinks to that directory,
# assuming you don't have any newer 1.0.x or 1.x releases. Also make a _latest_1_0_2 containing
# the latest (possibly unstable) 1.0.2.x version, and symlink _latest_1_0 and _latest_1 to it.
# Finally, create a _exact_1_0_2_4 if you have, for example, a 1.0.2.4 release of "tools".
#
# Each of those subdirectories is a package that can be loaded as "tools" by the client.
# File: tools/__init__.py
if '_original__import__' not in locals():
_original__import__ = __import__
def myimport(name, theglobals=None, thelocals=None, fromlist=None, level=-1):
if name.split('.')[0] != "tools":
return _original__import__(name, theglobals, thelocals,
fromlist, level)
if not currentversion:
raise Exception("After importing tools, you must "
"load a specific version by typing something like "
"'tools = tools.loadstable(\"0.1\")' .")
def withversion(name):
"""
Turn "tools[.anything]" into "<versionname>[.anything]" , where
<versionname> is something like 'tools._stable_0_1' .
"""
parts = name.split('.')
parts[0] = currentversion.__name__ # eg 'tools._stable_0_1'
return '.'.join(parts)
# "import tools[.whatever.whatever]"
if not fromlist:
# use <versionname> instead of "tools", but otherwise execute the
# import as expected
_original__import__(withversion(name), theglobals, thelocals,
fromlist, level)
# but return <currentversion> as the top-level package instead of
# returning tools as expected
return currentversion
# "from tools[.whatever.whatever] import thing": instead,
# "from <versionname>[.whatever.whatever] import thing", and
# return thing as expected
return _original__import__(withversion(name), theglobals, thelocals,
fromlist, level)
__builtins__["__import__"] = myimport
def loadstable(ver):
return _loadversion(ver, prefix="_stable_")
def loadunstable(ver):
return _loadversion(ver, prefix="_latest_")
def loadexact(ver):
return _loadversion(ver, prefix="_exact_")
def _loadversion(ver, prefix):
targetname = prefix + ver.replace('.', '_')
mainpackage = _original__import__("tools", globals(), locals(),
[targetname])
global currentversion
currentversion = getattr(mainpackage, targetname)
# Let users change versions after choosing this one
currentversion.loadstable = loadstable
currentversion.loadunstable = loadunstable
currentversion.loadexact = loadexact
return currentversion
currentversion = None
# In the user's code:
# This line makes "tools" be the stable 1.0.2 release.
import tools; tools = tools.loadstable('1')
# Now the user can work with tools as normal
from tools import foo
import tools.bar.bim
from tools.baz import bonk
