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    <p>Steve, you have a completely wrong mental model of what is a C function. </p> <pre><code>someType resultFunc = calloc( 1024, 1 ); memcpy( resultFunc, &amp;isNot, 1024 ); </code></pre> <p>From your code fragment, I can surmise that you think that you can copy function's compiled code into a block of memory, and then reuse it. This kind of thing smells of Lisp, except even in lisp you don't do it that way.</p> <p>In fact, when you say "&amp;isNot", you get a pointer to function. Copying the memory that pointer points at is counterproductive - the memory was initialized when you loaded your executable into memory, and it's not changing. In any case, writing someFunc() would cause a core dump, as the heap memory behing someFunc cannot be executed - this protects you from all sorts of viruses.</p> <p>You seem to expect an implementation of closures in C. That implementation is simply not there. Unlike Lisp or Perl or Ruby, C cannot preserve elements of a stack frame once you exited that frame. Even is nested functions are permitted in some compilers, I am sure that you cannot refer to non-global variables from inside those functions. The closes thing to closures is indeed C++ object that stores the state and implements operator(), but it's a completely different approach, and you'd still have to do things manually.</p> <p>Update: <a href="http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Nested-Functions.html#Nested-Functions" rel="noreferrer">here</a> is the relevant portion of GCC documentation. Look for "But this technique works only so long as the containing function (hack, in this example) does not exit."</p>
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    1. USJohn Millikin
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    1. COthanks for the link, my favorite quote was "If you try to call the nested function through its address after the containing function has exited, all hell will break loose."
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