VectorlikeStructs.jl
VectorlikeStructs.jl is a Julia package that lets structs behave like vectors — combining the numerical operations you expect from vectors with the convenient dot-indexing of structs.
Background
The package is especially useful when working with complex state vectors in robotics. For example, the state of a 6DoF rigid body is defined by its position p, velocity v, orientation q and angular velocities ω. Combining these quantities into one long vector is awkward to work with: accessing the angular rate along the y-axis, for example, requires some thinking to determine the right index.
Usage
Define a @vectorlike struct as follows:
@vectorlike struct SixDoFState
p
v
q
ω
end
Any SixDoFState now supports the common numerical operations you are used to from working with vectors, such as addition, matrix-vector multiplication and scalar multiplication. At the same time, you can still access the struct as you would expect: retrieving the y-axis component of the angular rate is as simple as x.ω[2].