An implementation of user-managed object pools in Julia.

This package is designed for use cases where some inner functions would need to allocate a large number of arrays which would not escape an outer function f. An object pool allows the user to obtain new objects with the new!, then allow them to be recycled with recycle!.

Consider this (contrived) example:

function f(pool, x::AbstractVector{T}) where T
    recycle!(pool)                   # reuse all arrays
    S = float(T)
    l = length(x)
    y = new!(pool, Vector{S}, l)     # taken from pool
    z = new!(pool, Matrix{S}, l, l)  # taken from pool
    @. y = abs2(x)
    z .= x .+ permutedims(x)
    z * y                            # the only allocated array
end

pool = ArrayPool() will save the relevant interim arrays and avoid allocation when necessary. If the function is called with various types, these will eventually accumulate too in pool.