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  1. Data Management
  2. DM-9938

Make some afw types hashable


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    • Sprint:
      AP F18-4, AP F18-5, AP F18-6
    • Team:
      Alert Production


      The C++11 containers unordered_set and unordered_map only work with hashable types, a concept that was itself added in C++11. Most afw value types were implemented before we adopted C++11, and therefore do not have a specialization of std::hash. Implementing std::hash will also make it easier to implement DM-7621, as the C++11 requirements for hash are stricter than the Python requirements.

      In most cases, hash can be quickly implemented by adopting a modified version of the algorithm from Effective Java, Item 9; the only difference between the C++ requirements and the Java ones is that hash functions are implied to be strictly deterministic before C++14, but the EffJ algorithm meets that criterion if the hash for all member variables does.

      The classes covered by this ticket are a subset (possibly taken from DM-9936) of the following types:

      • afw::cameraGeom::CameraPoint
      • afw::cameraGeom::CameraSys
      • afw::cameraGeom::CameraSysPrefix
      • afw::cameraGeom::Orientation
      • afw::coord::Coord and its subclasses
      • afw::coord::Observatory
      • afw::coord::Weather
      • afw::detection::Threshold
      • afw::geom::Angle
      • afw::geom::AngleUnit
      • afw::geom::Box
      • afw::geom::CoordinateBase and its subclasses
      • afw::geom::CoordinateExpr
      • afw::geom::Span
      • afw::geom::SpherePoint
      • afw::geom::polygon::Polygon
      • afw::image::Calib
      • afw::image::Color
      • afw::image::DefectBase
      • afw::image::Filter
      • afw::image::FilterProperty
      • afw::math::FitResults
      • afw::math::Function and its subclasses
      • afw::math::MaskedVector
      • afw::math::Statistics
      • afw::table::BaseRecord and its subclasses
      • afw::table::ConstFunctorKey
      • afw::table::FieldBase and its subclasses
      • afw::table::InputFunctorKey and its subclasses
      • afw::table::KeyBase and its subclasses
      • afw::table::Match
      • afw::table::OutputFunctorKey and its subclasses
      • afw::table::ReferenceFunctorKey
      • afw::table::SchemaItem
      • afw::table::io::Persistable
      • afw::table::io::PersistableFacade


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                • Assignee:
                  krzys Krzysztof Findeisen
                  krzys Krzysztof Findeisen
                  Jim Bosch
                  Jim Bosch, Krzysztof Findeisen
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