Abstract class for extracting features from arbitrary type FeatureSourceT to append to warehouse_ros::Query and warehouse_ros::Metadata for keying TrajectoryCache entries with. More...

#include "moveit/trajectory_cache/features/features_interface.hpp"

Detailed Description

Abstract class for extracting features from arbitrary type FeatureSourceT to append to warehouse_ros::Query and warehouse_ros::Metadata for keying TrajectoryCache entries with.

Template Parameters

FeatureSourceT. The object to extract features from.

The features that are extracted from the FeatureSourceT can be used to key the TrajectoryCache cache entries in a fuzzy and exact manner.

Users may implement this interface to add additional keying functionality to the cache beyond the ones provided by this package.

See also: TrajectoryCache

Usage ^^^^^ In order for a cache entry to be fetched using an implementation of FeaturesInterface<FeatureSourceT>, it must also have been put with the same implementation, as fetching a cache entry via some features requires that the features were added to the cache entry's metadata.

This typically means adding implementations of FeaturesInterface<FeatureSourceT> as arguments to the TrajectoryCache class's insertion methods. Or by using an appropriate CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT> that composes the set of FeaturesInterface<FeatureSourceT> instances you are concerned with.

Be sure to check the appropriate CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT> implementations' docstrings to see what FeaturesInterface<FeatureSourceT> they support, and make sure to only use a subset of those, unless you explicitly add additional metadata by providing the appropriate additional FeaturesInterface<FeatureSourceT> instances on cache insertion.

See also: CacheInsertPolicyInterface<KeyT, ValueT, CacheEntryT>

Composite Keys ^^^^^^^^^^^^^^ Multiple unique instances of FeaturesInterface<FeatureSourceT> can be used together to express composite key expressions, allowing you to constrain your match on a larger set of metadata (provided the metadata was added to the cache entry by a superset of the same set of FeaturesInterface<FeatureSourceT> instances used to fetch).

For example, the following can be used together to more completely key a cache entry:

A FeaturesInterface that appends workspace information
A FeaturesInterface that appends robot joint state
A FeaturesInterface that appends the final pose goal

You may then fetch that cache entry with a query formed from a subset of the instances used to key it, e.g.:

A FeaturesInterface that appends workspace information
A FeaturesInterface that appends robot joint state

WARNING: Care must be taken to ensure that there are no collisions between the names of the query or metadata being added amongst the different FeaturesInterface<FeatureSourceT> interfaces being used together.

A good way of preventing this is adding a prefix.

User-Specified Keys ^^^^^^^^^^^^^^^^^^^ You may also implement this interface to constrain a fetch query or tag cache entry metadata with user-specified parameters that do not depend on FeatureSourceT or any other arguments.

Simply ignore any passed arguments as necessary, and ensure that the correct information is appended in the append implementations as appropriate.

See also: constant_features.hpp

The documentation for this interface was generated from the following file:

moveit_ros/trajectory_cache/include/moveit/trajectory_cache/features/features_interface.hpp