Value and size constraints in DBus Introspection XML

[Lawrence D'Oliveiro]

On Tue, 20 Aug 2019 22:21:07 +0000, Matthew Bromley-Barratt wrote:

> Whenever I've found myself having interdependencies between message
> fields ... I've often found that that's an indication that I'm not
> constructing a very good schema.

Consider a simple example, where I have the heating in my office
controlled by a Raspberry π, and the server process accepts control
messages via D-Bus. I can send it a temperature at which to switch on,
and another temperature at which to switch off. The first temperature
must be lower than the second one. Getting these the wrong way round
could lead to a thermal runaway situation that makes my office a rather
unpleasant place to be in.