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  1. PO
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    <p>I'm not sure that <code>gettable()</code> copies the value to the Lua stack, I think it copies a reference or pointer of the value... (especially when that value is a table itself, that table 's content is not copied).</p> <p>And given that Lua may do magic processing, I believe your answer is no.</p> <p>Lua being <strong>free software</strong> you can <a href="http://www.lua.org/download.html" rel="nofollow">download</a> it and <strong>look in the source code</strong>. With <code>lua-5.2.0-rc4</code> the <code>lua_gettable</code> function is in file <code>src/lapi.c</code></p> <pre><code>LUA_API void lua_gettable (lua_State *L, int idx) { StkId t; lua_lock(L); t = index2addr(L, idx); api_checkvalidindex(L, t); luaV_gettable(L, t, L-&gt;top - 1, L-&gt;top - 1); lua_unlock(L); } </code></pre> <p>so the actual work is done by <code>luaV_gettable</code> from file <code>src/lvm.c</code> which is </p> <pre><code>void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) { int loop; for (loop = 0; loop &lt; MAXTAGLOOP; loop++) { const TValue *tm; if (ttistable(t)) { /* `t' is a table? */ Table *h = hvalue(t); const TValue *res = luaH_get(h, key); /* do a primitive get */ if (!ttisnil(res) || /* result is not nil? */ (tm = fasttm(L, h-&gt;metatable, TM_INDEX)) == NULL) { /* or no TM? */ setobj2s(L, val, res); return; } /* else will try the tag method */ } else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_INDEX))) luaG_typeerror(L, t, "index"); if (ttisfunction(tm)) { callTM(L, tm, t, key, val, 1); return; } t = tm; /* else repeat with 'tm' */ } luaG_runerror(L, "loop in gettable"); } </code></pre> <p>so I think the answer is no. However, you could patch or enhance the code. I don't understand why the question bothers you. Only simple data is copied (very quickly), unless magic occurs (and the magic i.e. metatable is an essential part of Lua semantics); aggregate data content is not copied.</p>
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    1. POAccess Table passed from Lua in C without Copying the values
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    1. USBasile Starynkevitch
    1. USBasile Starynkevitch
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    1. COHi Basile, I have added the code to my question. You can have a look to it.
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      1. USRahul
    2. COI have also added comments to let you understand the working of code.
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    3. COIt bothers me because I have to analyze the TCP packets and I want my code to be efficient. Copying of data in packet may lead to problems as I have limited amount of memory and I have to reduce the copy.
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