Sending a non-existent/not-defined signal

[Lawrence D'Oliveiro]

On Sun, 27 Mar 2022 14:15:14 +0200, Sergio Costas wrote:

> For several reasons I need to notify another program using DBus and
> a signal, and I found that I can use "emit_signal()" over a DBus
> object in my standard service/object to send a "random signal" (this
> is, a signal whose name isn't defined in any interface of that DBus
> object).

How do other apps discover what interfaces you define/support? They do
it through introspection. But there seems to be no requirement that
D-Bus apps actually support introspection. So what is there to prevent
you from making up a new random interface on the spot, defining a new
signal which you then send?