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    <p>Yeah. One of the best things I've encountered in lua is the <strong>anything as references</strong> property.</p> <p>There's nothing wrong with the way you are using your <code>key</code>s in the table.</p> <h3>From <a href="http://www.lua.org/pil/2.5.html" rel="noreferrer">Lua PiL</a></h3> <blockquote> <p>Tables in Lua are neither values nor variables; they are objects.You may think of a table as a dynamically allocated object; your program only manipulates references (or pointers) to them. There are no hidden copies or creation of new tables behind the scenes.</p> </blockquote> <p>In your example, you haven't passed any argument to the function, so basically, it'll be useless in your case to have functions as reference in the program. On the other hand, something like this:</p> <pre><code>fn1 = function(x) print(x) end fn2 = function(x) print("bar") end t[fn1] = "foo" t[fn2] = "foo" for i, v in pairs(t) do i(v) end </code></pre> <p>does have its uses.</p> <blockquote> <blockquote> <p>Can Lua reuse function references once they are out of scope?</p> </blockquote> </blockquote> <p>As long as your parent table is in scope, yes. Since tables are created and manipulated but not copied, so there isn't a chance that your function reference can be deprecated from the table index memory. <em><strong>I'll edit this answer later after trying it out actually too.</strong></em></p> <blockquote> <blockquote> <p>Can this create any issues or is it considered a bad practice due to some reason?</p> </blockquote> </blockquote> <p>It's just considered a bad practise because users familiar with other languages, like <code>C</code>, <code>python</code> etc. tend to have array in mind when reading tables. In <a href="/questions/tagged/lua" class="post-tag" title="show questions tagged &#39;lua&#39;" rel="tag">lua</a> you have no such worries, and the program will work perfect.</p> <blockquote> <blockquote> <p>I don't know if I can rely on the uniqueness of the function references.</p> </blockquote> </blockquote> <p>Why?</p>
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    1. POCan lua function references be used as table keys?
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    1. COThanks for the detailed answer! Much appreciated! I doubted the uniqueness of function references as there may be a rare case where two functions have same body and the Lua interpreter may decide to make it a single reference to save memory, as happens in case of empty objects and same strings in most languages. That said, the case of two functions with same bodies should not arise in most projects. Other reason was can Lua use the same hashcode(the one seen by printing function or calling tostring(fn)) for other functions. But as you clarified, this is unlikely unless it is gc'ed.
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    2. COEven with the same body, as long as you use separate `name`s for them, they **WILL** be assigned new reference.
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    3. CO@BackinaFlash that is not true in general. That was true for the 5.1 official interpreter; but is NOT for 5.2. I believe it was up to the individual implementaton.
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