Re: Why doesn't dbus-handle-event catch all errors?

[Daniel Colascione]

On 02/20/2014 11:22 PM, Michael Albinus wrote:
> Daniel Colascione <address@hidden> writes:
>
> > dbus-handle-event uses a condition-case that catches dbus-error, but
> > errors in general. Why don't we send all lisp errors from handler
> > functions back to callers as dbus errors?
>
> Because they aren't dbus errors. If your handler has some stupid code
> like `(car 42)', the resulting lisp error `(wrong-type-argument listp 42)'
> shouldn't be shown as *dbus* error.

Any nonlocal exit of a dbus handler message handler ought to be a dbus 
error: that nonlocal exit results in a program that expects a dbus reply 
not getting one at all.

> You're free to write a handler which returns any error as dbus error, if
> your program logic requires this.

The only reasonable implementation of a dbus handler is one that 
transforms lisp errors to dbus errors, so why not do that automatically 
in dbus.el? Silently swallowing lisp errors is the less common case, and 
if a program needs to do that, it can wrap its logic in ignore-errors 
inside the handler.