New method for 'Base.sum'

[nilshg]

Yes this is very common if one wants to extend a function to work with one’s own type. This avoids shadowing the function, we just had this discussion yesterday:

Step!() remains strangely unfound if buried inside another method

As Steven said you are shadowing the function - think of it as overwriting the definition, so step! is not related to DynamicalSystems.step! at all. Here’s a simple example: julia> struct A end julia> sum(x::A) = 5 sum (generic function with 1 method) julia> sum(A()) 5 julia> sum([1,2,3]) ERROR: MethodError: no method matching sum(::Vector{Int64}) You may have intended to import Base.sum As you see, the sum I created there has only 1 method, so there is nothing for multiple dispatch to do.…