| 86 | If the test for whether a location is in a region is expensive (e.g. if it uses |
| 87 | polygon overlap), we may want to cache the membership (similar to caching the |
| 88 | location's hierarchy path). A location can belong to more than one region, so |
| 89 | this would be a list of regions (specified by their region location ids). Would |
| 90 | need to record both positive and negative results, i.e. if we test a location |
| 91 | against a region and find it's not in that region, we need to record that to |
| 92 | avoid redoing the test. The cache would be invalidated if the location's |
| 93 | parentage or lon, lat changes. This needs careful consideration, to handle invalidating |
| 94 | the region test results if the region changes. |
| 95 | |