Nobody wants to set this parameter. It is necessary because the old
API allowed `awful.rules` to be used with random for random matching.
This stopped "really" working between the 3.4 and 3.5 release because
the code started to accumulate "corner case" fixes aligned with the
client properties. v4.0 added more ordering and v4.3 added external
sources. After this, it is unusable with external objects, but
`gears.matcher` handle this use case very well.
In a perfect world we would have pure expression matching, but
that's problematic with all the "metaness" of the code. For now,
this adds an imperfect way to match the minimum and maximum of
number properties.
It will be used by the screen rules for the DPI and size properties.
This is hardcoded in `awful.rules`, but cannot be shared due to the
priority corner cases. Given in the long run any "standard" priority
should use the topological sort API, better not try to share *that*
code.
It is now possible to add and remove rules. This is superior to how
`awful.rules` originally handled rules because modules can now
assume adding and removing rules works.
The reason for the methods rather than `table.insert` is partially
because future commits will add signals. In turn, this will allow
`gears.matcher` to be extended by module using it using the extra
"introspection" made possible by the signals.
Emmanuel Lepage Vallee