How to resolve the algorithm Multiple distinct objects step by step in the Lua programming language

Published on 12 May 2024 09:40 PM

How to resolve the algorithm Multiple distinct objects step by step in the Lua programming language

Table of Contents

Problem Statement

Create a sequence (array, list, whatever) consisting of n distinct, initialized items of the same type. n should be determined at runtime. By distinct we mean that if they are mutable, changes to one do not affect all others; if there is an appropriate equality operator they are considered unequal; etc. The code need not specify a particular kind of distinction, but do not use e.g. a numeric-range generator which does not generalize. By initialized we mean that each item must be in a well-defined state appropriate for its type, rather than e.g. arbitrary previous memory contents in an array allocation. Do not show only an initialization technique which initializes only to "zero" values (e.g. calloc() or int a[n] = {}; in C), unless user-defined types can provide definitions of "zero" for that type. This task was inspired by the common error of intending to do this, but instead creating a sequence of n references to the same mutable object; it might be informative to show the way to do that as well, both as a negative example and as how to do it when that's all that's actually necessary. This task is most relevant to languages operating in the pass-references-by-value style (most object-oriented, garbage-collected, and/or 'dynamic' languages). See also: Closures/Value capture

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Step by Step solution about How to resolve the algorithm Multiple distinct objects step by step in the Lua programming language

Source code in the lua programming language

-- This concept is relevant to tables in Lua
local table1 = {1,2,3}

-- The following will create a table of references to table1
local refTab = {}
for i = 1, 10 do refTab[i] = table1 end

-- Instead, tables should be copied using a function like this	
function copy (t)
    local new = {}
    for k, v in pairs(t) do new[k] = v end
    return new
end

-- Now we can create a table of independent copies of table1
local copyTab = {}
for i = 1, 10 do copyTab[i] = copy(table1) end


  

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