# -*- coding: utf-8 -*- """ If we have a run callable passed to the constructor or set as an attribute, but we don't actually use that (because ``__getattribute__`` or the like interferes), then when we clear callable before beginning to run, there's an opportunity for Python code to run. """ import greenlet g = None main = greenlet.getcurrent() results = [] class RunCallable: def __del__(self): results.append(('RunCallable', '__del__')) main.switch('from RunCallable') class G(greenlet.greenlet): def __getattribute__(self, name): if name == 'run': results.append(('G.__getattribute__', 'run')) return run_func return object.__getattribute__(self, name) def run_func(): results.append(('run_func', 'enter')) g = G(RunCallable()) # Try to start G. It will get to the point where it deletes # its run callable C++ variable in inner_bootstrap. That triggers # the __del__ method, which switches back to main before g # actually even starts running. x = g.switch() results.append(('main: g.switch()', x)) # In the C++ code, this results in g->g_switch() appearing to return, even though # it has yet to run. print('In main with', x, flush=True) g.switch() print('RESULTS', results)