Exclude option/operator for MapCSS

[naoliv]

Could MapCSS support some kind of option/operation to exclude other tags?

For example, I would like to search/validate objects that only have name=Foo or surface=paved or area=yes, without any other tags.

If the rule has [name] + the exclude option/operation, it shouldn't match anything except the object that has only a name key.

It should work the same way with multiple key/values.
For example, [name][surface][<magical exclude operator>] should match objects with only name + surface.

[bastiK]

What about an eval function that returns the number of tags?

[naoliv]

Seems good.
It should give the same result, from what I see, and also opens up new possibilities for testing/validating/processing the data.

[bastiK]

In 7237/josm:

fixed #10130 - add mapcss expression to get number of tags

new mapcss expression to print debugging output to the console