Re: continue keyword - since there is goto now, maybe reconsider continue?
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- Subject: Re: continue keyword - since there is goto now, maybe reconsider continue?
- From: Sean Conner <sean@...>
- Date: Wed, 8 Jan 2014 19:13:26 -0500
It was thus said that the Great Jonas Thiem once stated:
> Since there is now a working goto in Lua, I suppose there is no longer
> any technical reason why there is no continue.
>
> In case that's true, I would like to point out that goto as a
> continue-replacement isn't very nice:
>
> It needs twice the lines (goto statement + label), and you need to
> make up a unique jump label per loop if you got multiple loops in a
> function with such a continue workaround.
>
> Also, you can easily mix up your jump labels and suddenly jump into
> one of the other loops and generate non-obvious, huge bugs with that.
>
> What about natively supporting continue in an upcoming Lua version? I
> would be using it a lot, I do in all other programming languages which
> usually have it.
Just an observation, but ...
Since Lua has tail call optimization, you could always implement a loop
with a "continue" statement as:
function only_process_lines_starting_with_dollar_sign(input)
local line = input:read("*l")
if line == nil then
return
end
if not line:match("^%$") then
-- continue, skipping the current line
return only_process_lines_starting_with_dollar_sign(input)
end
-- some processing
if some_condition_we_want_to_skip_this_line(line)
return only_process_lines_starting_with_dollar_sign(input)
end
return only_process_lines_starting_with_dollar_sign(input)
end
-spc (Oddly, I've found I don't really miss continue in Lua ... )