Improve submodule reloading

[deathaxe]

This commit provides a change to clear the sys.modules cache before
importing any local package/module. This causes python to reload all
modules as soon as the FileManager.py is reloaded/imported by ST.

It is to ensure fluent plugin updates even if global variables or
module names change.

Nothing else is needed to instantly update all submodules during
development but saving the FileManager.py

This strategy is used by A File Icon and GitGutter for instance.

[math2001]

Nice, I agree that reloading needed to be better in FileManager.

Though, is there an idiomatic way to reload FileManager.py for any python file I save that's within FileManager? Here's what I'm doing right now (with your system running):

import os
import sys
import imp
import sublime_plugin


def reload_filemanager(view):
    file_name = view.file_name()
    assert file_name is not None, "post save and file_name is None?"

    if "FileManager.FileManager" not in sys.modules:
        print("FileManager not loaded, no reloading")

    if not file_name.endswith(".py"):
        return

    filemanager_root = os.path.join(sublime.packages_path(), "FileManager")

    if filemanager_root not in file_name:
        return

    imp.reload(sys.modules["FileManager.FileManager"])


class Hooks(sublime_plugin.EventListener):
    def on_post_save(self, view):
        reload_filemanager(view)

Thoughts? imp is deprecated from >= 3.4, so I'll also document an alternate version for 3.8 (just use importlib instead) if you think this is good.

Neat PR once more ♥️

[deathaxe]

I personally use the AutomaticPackageReloader to reload submodules during development instead of hacking around something new for each plugin.

I am not sure whether calling imp.reload() only is sufficient in all situations. You may end up in changes not being picked up correctly as python may still use old instances/references depending on module load order.

The trick with this PR is to clear the cache while ST is reloading the FileManager.py, so python reimports all submodules in the correct order to make sure all references are updated correctly.

Your hook would need to call sublime_plugin.reload_plugin() to make sure everything is updated well. This is what AutomaticPackageReloader does.