daemondo defeats purpose of launchd?

[markd at macports.org]

James Berry <jberry at macports.org> writes:
>For those cases where startupitem.executable cannot be used, daemondo  
>also supports the startupitem.pidfile commands that allow the  
>process' pidfile to be monitored: daemondo will read the pidfile and  
>watch for the death of that process.

>So daemondo, and thus launchd, will be aware of the daemon process  
>death (and be able to restart the daemon process) only under two  
>circumstances:
>
>	(1) startupitem.executable was supplied (thus daemondo starts the  
>process)
>	(2) startupitem.pidfile was supplied (thus daemondo reads the  
>process id)
>
>Under all other circumstances, daemondo will not know that the daemon  
>process has died, and will not exit when the process does die, and  
>thus launchd won't restart the process since it doesn't  know it  
>died. Put another way, if daemondo can know the process has died,  
>then launchd will know too, but not otherwise.
>
These statements seem incompatible with ....
>
>The pidfile keyword is likely used only if executable is not.

This one.

Looks to me like startupitem.pidfile must be set for a deamon to be
tracked whether it is executable startupitem or not.  And the man page
says startupitem.pidfile is "particularly useful" for
startupitem.executable.  Can you explain this?

Mark