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On Mon, 08 Jan 2007 16:24:45 -0600, Michael Newberry <mnewberry@mirametrics.com> wrote:
It would be nice if one or more assignments could be evalulated but ignored left to right, so long as there is a value to test before "do": 

    while <assignment>, str ~= nil do
        --[code]
    end

or just evaluate str rather than str ~= nil.

Michael
This isn't really pressing, but the loop syntax topic reminded me of something. I've been meaning to implement "anaphoric while" (and if) since the token filter stuff started to take off. I use the sort of idiom mentioned above (at least in the single- assignment, test-against-nil case) enough that I think it would be worth having. Something that transforms this: 

	awhile <expression>[, <var>] do
		<body>
	end

into this:

	do
		local it
		while true do
			<var> = <expression>
			if <var> then
				<body>
			end
		end
	end
(If <var> is omitted above, then "it" (or some other default) is used; otherwise, the first two lines and the last line need not 
be emitted.)

So you'd have something (referring again to the other topic) like this:

	awhile S:Next(), str do
		--[code]
	end
Has anybody done this or something similar? I may have a go at it now that ftools and friends are out, but I haven't done anything with these yet and it's not clear if such a construct would play nice, due to the possiblity of nesting, as well as balancing the "awhile" and "end" properly. Are my worries unfounded? Maybe I missed a good example? I suppose I'd attempt it sooner or later, but it would be nice to know ahead of time if I'm going to be beating my head against the wall. 

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