The idea would be to allow to create {{ Projection SearchProjection <T>}} objects from a {{SearchTarget}}, and use these objects when creating a query: {{.asProjections( projectionObject1, projectionObject2, ...)}}.
This would allow three things:
* Implementation parameterized projections, where naming the projection is not enough, and we need to pass paramters to it. See for example the spatial distance projections, where we need to pass a latitude and longitude: HSEARCH-3190
* Enabling of disabling bridges in projections; see HSEARCH-3223
* Type-safe projections, i.e. passing typed references to the {{asProjections()}} methods, and get a {{SearchQuery<Pair<T, U>>}}, or {{SearchQuery<Triplet<T, U, V>>}}, and so on depending on the number of parameters. This would obviously only be possible for a small number of parameters (say, up to 5), because we would have to declare and implement one {{asProjections()}} method for each possible number of parameters. Note that, in order to allow that, we should at the very least make {{asProjections}} set the query type to {{SearchQuery<? extends List<?>>}} instead of the current {{SearchQuery<List<?>>}}.
See also HSEARCH-2265 |
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