On 28/01/11 13:07, Roberto Ierusalimschy wrote: [...] > In Lua, we favor generic and powerful constructs. Actually, a 'goto' > would be almost perfect. But its interaction with variable scoping > is quite confusing in a language with first-class functions like Lua. > Labeled breaks seem the next best thing, as it allows any forward goto > that does not enter a variable scope. Personally I think 'goto' fits very nicely within the Lua ethos of providing mechanism, not policy, but I think people already know my stance on this... My particular use case is to be able to do arbitrary jumping between points within a single function --- backwards as well as forwards. I'm a little leery of the labelled break concept because it doesn't support jumping backwards. It's certainly possible to do perpetrate something like this: while true do :scope0_e: do :scope0_c: if fn1() then break :scope0_e: end if fn2() then break :scope0_c: end while true do :scope1_e: do :scope1_c: if fn3() then break :scope0_e: end if fn4() then break :scope0_c: end if fn5() then break :scope1_e: end if fn6() then break :scope1_c: end break end break end A break to *_e jumps to the end of the scope, a break to *_c jumps to the beginning of the scope. To my eye that sort of thing is even harder to read and more evil than an honest goto, plus I don't believe it will work in all cases --- I don't think that forward jumps across targets of backward jumps can be done with this idiom. -- ┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ───── http://www.cowlark.com ───── │ │ life←{ ↑1 ⍵∨.^3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ } │ --- Conway's Game Of Life, in one line of APL
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