Named arguments without natural defaults in Julia

Question

The question is about 'best practice' in Julia. I have read this and this. I have a function

function discount_rate(n, fv, pmt, pv; pmt_type = 0)
...
end

The problem right now is I have to call the method like so

discount_rate( 10, 10, 10, -10 )

It's not clear what these arguments mean -- even I forget. What I'd love to do is write

discount_rate( n = 10, fv = 10, pmt = 10, pv = -10 )

That's clearer: easier to read and understand. But I can't define my method by making these arguments keywords arguments or optional arguments because they don't have natural defaults. From the point of view of design, is there a recommended way around this?

Answer 1

Could do the following:

function discount_rate(;n=nothing,fv=nothing,pmt=nothing,pv=nothing,pmt_type=0)
    if n == nothing || fv == nothing || pmt == nothing || pv == nothing
        error("Must provide all arguments")
    end
    discount_rate(n,fv,pmt,pv,pmt_type=pmt_type)
end

function discount_rate(n, fv, pmt, pv; pmt_type = 0)
    #...
end