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POHow to handle C++ exceptions when calling functions from Lua?
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copied!<p>I have a working C++ function that I am able to call from Lua. To demonstrate my problem here is an example:</p> <pre><code>int PushHello(lua_State *L){ string str("Hello"); lua_pushlstring(L, str.data(), str.length()); return 1; } </code></pre> <p>Note: I know I don't have to use string variable there, but it is there to demonstrate the problem.</p> <p>Here are my two problems:</p> <ol> <li><p>When I call this function from Lua string constructor may throw an exception. Is that a problem? Will Lua handle it and unwind the Lua stack properly? I don't think so. How can I solve that? Do I need to add <code>try/catch</code> around all such code and convert the exception to lua_error? Is not there a better solution?</p></li> <li><p>Another problem that I have probably solved by compiling Lua as C++ is when <code>lua_pushlstring()</code> calls <code>lua_error()</code> string destructor would not be called if longjmp was used. Is the problem solved by compiling as C++ and throwing exceptions instead of using longjmp?</p></li> </ol> <p>To clarify, possible solution I can see to problem 1 would be this:</p> <pre><code>int PushHello(lua_State *L){ string str; try{ str.assign("Hello"); catch(exception &e){ luaL_error(L, e.what()); } lua_pushlstring(L, str.data(), str.length()); return 1; } </code></pre> <p>But that is very ugly and error prone as <code>try/catch</code> would need to be added to many places. It could be done as a macro and put around every command that can throw, but that would not be much nicer.</p>

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