silent no-op if you forget to call run()

[oconnor663]

That sucks.

[oconnor663]

We could add a destructor to command objects that prints a warning if they've never been run. (I think the Rust equivalent of this would be the #[must_use] attribute.

[oconnor663]

God I do this all the time in the repl...

EDIT: Where a destructor warning might not even help :p