Module talk:Color contrast

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Making the lum function accessible from modules

I've made the lum function accessible from modules by changing the code from:

function p.lum(frame)
	return color2lum(frame.args[1] or frame:getParent().args[1])
end

to:

function p.lum(frame)
	local args = frame.args[1] or frame:getParent().args[1]
	return p._lum(args)
end

function p._lum(args)
	return color2lum(args)
end

The changes are on the sandbox and will implement them if there are no comments. --Gonnym (talk) 11:03, 6 January 2019 (UTC)

@Gonnym: That looks like a very sensible and useful improvement. My only reservation is that passing the parameters as a table gives the person wanting to import the routine no idea of what values/types to supply to the routine without having to read through all of the code to determine them. In general I'd usually recommend either documenting a brief list of required values for the args table or passing the parameters as a list of obviously-named variables rather than a table. But that's just a minor point and shouldn't stop you from updating the main module. --RexxS (talk) 13:03, 6 January 2019 (UTC)
@RexxS: I don't mind doing either if that helps. I just followed the current style used for the other three public functions. Do you want me to change _lum(args) to _lum(color)? --Gonnym (talk) 13:27, 6 January 2019 (UTC)
@Gonnym: Sorry, my confusion: now I've looked harder at it, you're actually passing a string representing the colour, not a table (which is what args would most commonly indicate). I would suggest:
-- use {{#invoke:Color_contrast|somecolor}} directly or {{#invoke:Color_contrast}} from a wrapper template:
function p.lum(frame)
	local color = frame.args[1] or frame:getParent().args[1]
	return p._lum(color)
end

-- This exports the function for use in other modules.
-- The colour is passed as a string:
function p._lum(color)
	return color2lum(color)
end
I know we can put fuller information in the documentation, but I always suggest leaving small annotations in the code to help any re-users.
You could also write p._lum = color2lum instead of the second function definition, but setting it out explicitly, as you have done, helps whoever is importing the module to see what parameters to supply. Cheers --RexxS (talk) 15:41, 6 January 2019 (UTC)
Sure, looks good. I'll update the sandbox version. --Gonnym (talk) 15:43, 6 January 2019 (UTC)
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