Describe the bug

Given a simple dodo.py like this:

from doit.action import CmdAction

def action_thing():
    print('I was called.')
    return 'echo hello world!'

def task_testing():
    return {
        'actions': [
            CmdAction(action_thing)
        ],
        'verbosity': 2,
    }

You can see that action_thing gets called twice (the print line is run twice). The root cause appears to be that CmdAction.action is defined as:

    @property
    def action(self):
        if isinstance(self._action, (str, list)):
            return self._action
        else:
            # action can be a callable that returns a string command
            ref, args, kw = normalize_callable(self._action)
            kwargs = self._prepare_kwargs(self.task, ref, args, kw)
            return ref(*args, **kwargs)

so a self.action call actually runs the callable. And self.action is called in several places. For example, line 283 is:

if isinstance(self.action, list):

This can be problematic in some circumstances. For example, I have a callable that makes a REST call to get a version number and then uses that to do some other things. Obviously I don't want to make that call twice.

Environment

1. OS: Linux (Debian 11)
2. python version: 3.9
3. doit version: 0.36.0

suggestion: call the callable once and cache the result. A @functools.cache might do the trick.