Config paths that point to non-existing config files

[hdevalence]

After implementing Configurable<FooConfig> for FooCommand to have config_path return the application's config path (and tweaking things so this is actually called, see #79 for notes on my confusion), my application exits with a hard error if a config file does not exist at the supplied path.

Ideally I would like the application to attempt to load a config from a supplied path, or use a set of defaults if that file doesn't exist.

The config_path documentation doesn't give details, but is it the responsibility of the config_path function to check whether the file exists and return None if not, or should it return the expected path for a config file, and have the config loading logic have responsibility for gracefully handling the case where the config is not supplied?

[tarcieri]

This is a gross oversight in abscissa::command::EntryPoint. My apologies.

I agree it should attempt to source config_path from the underlying toplevel command it wraps unless one is provided explicitly as a command-line argument.

The intention is definitely that you can simply supply a path to load without checking it exists, and the framework will handle the file's absence by printing an error. If you would like to print a custom error rather than letting the framework handle it, you can check for the file's existence in advance (however note you won't get called in the event -c is passed).