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Writing cleaner code without break or continue
Conditionals and loops example from a Well House Consultants training course
More on Conditionals and loops [link]
Source code: whilly Module: U103
--[[
The "goto" statment - in languages that still support it - is regarded with distain by Computer Scientists as it makes for spaghetti code - hard to follow and going all over the place! In some ways, loop controls "break" and "continue" ("last", "next" and "redo" in Perl; "next", "redo", "retry" and "break" in Ruby) are also forms of the goto. They are not <i>as</i> bad in that they only jump within a limited area, but on the other hand many forms don't involve labels so that there's no clue at the destination point in your code that it's an arrival point. Having slagged off these statements (and in reallity I'm being a pedantic computer scientist by doing so - I use them personally from time to time!) I had better off you the alternative. Written on yesterday's Lua course as a demonstration - here's a while loop that has an ugly break in it ... ]] j=14 while 1 do print (j) if j > 20 then break end j = j + 1 end print ("done") --[[ ... and here's the alternative using a control variable. ... ]] j=14 running = true while running do print (j) if j > 20 then running = false else j = j + 1 end end print ("done") --[[ That code being longer, but purer and easier to maintain ]] Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Lua * Lua Programming * Lua Programming Also available on on site courses for larger groups Books covering this topic
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