On Tue, Dec 30, 2014 at 12:02:32AM +1100, Chris Angelico wrote:
On Mon, Dec 29, 2014 at 11:46 PM, Nick Coghlan <ncoghlan@gmail.com> wrote:
However, even today, it's not particularly difficult to create custom launch scripts that initialise __main__ with a few different modules based on what you plan to work on and then set os.environ["PYTHONINSPECT"] = "1" to drop into the interactive interpreter:
$ python3 -c "import sys, os; os.environ['PYTHONINSPECT'] = '1'"
sys, os (<module 'sys' (built-in)>, <module 'os' from '/usr/lib64/python3.4/os.py'>)
Once again, that's fine for sys and os, which won't take long to import. For this to work with _every_ module on the system, you'd need to couple it with a lazy import mechanism. We had some proposals along those lines recently... what happened to them?
I just threw this lazy import proxy object together. I haven't tested it extensively, but it seems to work: from types import ModuleType class LazyImporter(ModuleType): def __init__(self, name): self._module = None self.__name__ = name self.__package__ = None def __getattr__(self, name): if self._module is None: module = self._module = __import__(self.__name__) self.__package__ = module.__package__ else: module = self._module return getattr(module, name) def lazy_import(name): from sys import modules if name in modules: return modules[name] else: return LazyImporter(name) Usage: decimal = lazy_import('decimal') decimal.Decimal If the module has already been cached, you get the module itself, otherwise you get a proxy. This was so obvious and simple, I cannot believe I am the first to have thought of it. Perhaps there is something similar that has been extensively used and tested in the real-world that the standard library could steal? -- Steven