CoffeeScript IIFEs

Immediately-Invoked Function Expressions are an easy way to hide your variables, preventing collisions with your code or the code of others. In JavaScript you'll see the following a lot:

	(function () {
	var nonGlobalVar = "foo";
	var alsoNonGlobal = "bar"
	console.log(nonGlobalVar + " " + alsoNonGlobal);
	})();

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In CoffeeScript the syntax can be the same; enclose the function in parens, and put parens after it to call it. It's ugly, though:

	(->
	nonGlobalVar = "foo"
	alsoNonGlobal = "bar"
	console.log "#{nonGlobalVar} #{alsoNonGlobal}")()

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CoffeeScript has the do keyword, though, and it provides a cleaner way to do this:

	do ->
	nonGlobalVar = "foo"
	alsoNonGlobal = "bar"
	console.log "#{nonGlobalVar} #{alsoNonGlobal}"

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If you're passing an argument the ugly way you'd put the closing paren at the same level as the IIFE's code block; this looks a little wonky to me, and the trailing paren looks lonely (odd for a Lisp person to say, huh?

	((s) ->
	nonGlobalVar = "foo"
	alsoNonGlobal = "bar"
	console.log "#{nonGlobalVar} #{alsoNonGlobal} #{s}"
	)("baz")

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The do version requires the variable to be set at the point of the do. I think I still prefer this method, but it reads a little funny to me:

	do (s = "baz") ->
	nonGlobalVar = "foo"
	alsoNonGlobal = "bar"
	console.log "#{nonGlobalVar} #{alsoNonGlobal} #{s}"

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