[Python-Dev] cpython: Introduce importlib.util.ModuleManager which is a context manager to

[Eric Snow]

On Wed, May 29, 2013 at 2:22 PM, Brett Cannon <brett at python.org> wrote:
> So module_to_init it is unless someone can convince me the bikeshed is
> a different colour.

Whatever the name is, it should reflect what is happening during the
with statement, and more particularly that the thing will end at the
end of the with statement.  managed_module() seems fine to me though
it could still imply the lifetime of the module rather than the
management.  During the with statement the module is managed, and I
expect it's clear that the management is relative to the import
system.

However, it could also make sense to split the function into two
pieces: getting the module and handling it properly in the face of
exceptions in a with statement.  So, importlib.util.get_module() and
ModuleType.managed():

  class Loader:
    def load_module(self, fullname):
      module = importlib.util.get_module(fullname)
      with module.managed():
        # Load/initialize the module
        return module

If ModuleType.managed() returned the module, you could do it on one line:

  class Loader:
    def load_module(self, fullname):
      with importlib.util.get_module(fullname).managed() as module:
        # Load/initialize the module
        return module

On second thought, that "one-liner" is a little too busy.  And if it's
a problem as a method on ModuleType, make it
importlib.util.managed_module():

  class Loader:
    def load_module(self, fullname):
      module = importlib.util.get_module(fullname)
      with importlib.util.managed_module(module):
        # Load/initialize the module
        return module

It would be nice to have both parts in one function.  It would be less
boilerplate for the "common" case that way, is easier to read, and
eliminates the risk of someone not realizing they need both parts.
However, I'm not sure it buys us that much, the separate-part approach
helps keep the two concepts distinct (for better or for worse), and
each piece could be separately useful.  Maybe have a third function
that wraps the other two or have managed_module() accept strings (and
then call get_module() internally).

-eric