Perhaps stop punning on Base functions?

[KristofferC]

FEMBasis does some "puns" on Base functions, for example:

        function Base.size(::Type{$name})
            return ($D, $N)
        end

        function Base.size(::Type{$name}, j::Int)
            j == 1 && return $D
            j == 2 && return $N
        end

        function Base.length(::Type{$name})
            return $N
        end

length is typically defined for collections (or at least when the instance of the type is a collection). AbstractBasis is not iterable and it probably shouldn't be. Instead of defining these functions I think they should have their own names ndim, nbasis.
Overloading Base functions are typically meant so you can write generic code but there is no way to write generic code with puns like this.

[KristofferC]

Another thing is that length(...) is usually the same as prod(size(...)) which this breaks.

[TeroFrondelius]

Ok. This needs to change. Do you have a proposal or an idea how to change?

[ahojukka5]

Yes, we could do this somehow differently. This convention originates from the need to know proper dimensions of workspace when evaluating e.g. basis functions.