Dustin Ryan-Roepsch Dustin Ryan-Roepsch - 1 month ago 21
Ruby Question

Using a case statement to assign multiple variable in ruby

I'm implementing an HSV to RGB function in ruby, and I was hoping for syntax like this:

def hsv_to_rgb(h, s, v)
if (h == 0) then return 0, 0, 0 end
c = v * s
hp = h / 60.0
x = c * (1 - (hp % 2 - 1).abs)
r, g, b = case hp
when 0..1
c, x, 0
when 1..2
x, c, 0
when 2..3
0, c, x
when 3..4
0, x, c
when 4..5
x, 0, c
else
c, 0, x
end

m = v - c
return r + m, g + m, b + m
end


however, when I attempt to run this in Jruby I get the following error message:


SyntaxError: julia2.rb:60: syntax error, unexpected '\n'
when 1..2


Does something like this syntax exist in ruby?
Thanks!

Answer

Your return values in the case statement are not accepted by the ruby engine. I think you want to return an array... using the [] perhaps?

Like this:

def hsv_to_rgb(h, s, v)
    if (h == 0) then return 0, 0, 0 end
    c = v * s
    hp = h / 60.0
    x = c * (1 - (hp % 2 - 1).abs)
    r, g, b = case hp
        when 0..1
            [c, x, 0]
        when 1..2
            [x, c, 0]
        when 2..3
            [0, c, x]
        when 3..4
            [0, x, c]
        when 4..5
            [x, 0, c]
        else
            [c, 0, x]
        end

    m = v - c
    return r + m, g + m, b + m
end
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