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lazy operators / short circuit evaluation
Functions. example from a Well House Consultants training course
More on Functions. [link] Source code: lazy Module: U106
--[[ In Lua, if a partial expression evaluates to true the following section will NOT be evaluated if it follows an or because the whole thing cannot be true. If a partial expression evaluates to false, the following section will NOT be evaluted if it follow an and because the whole thing must be true. If you find this a bit theoretic, try a real life example ... If you're going to buy a kebab OR Fish and Chips and you find the kebab shop open, you won't bother to carry on up the road to the chippy because you have already met your needs. If you require a hammer AND nails, but you can't find a hammer, you won't go and search for the nails because even if you find them, they're not going to be much use to you! ]] function agelimit(incoming) return type(incoming) == "number" and incoming or 18 end print (agelimit(10)) print (agelimit(12)) print (agelimit("fourteen")) print (agelimit(16)) --[[ ---------------------- Sample Output [trainee@easterton u106]$ lua lazy 10 12 18 16 [trainee@easterton u106]$ ]] 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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