logancapaldo

I see. What I was worried about was a version of the code you didn't actually write (casting the ptrdiff_t result to a [u]intptr_t, not casting the pointers first).

What if it's not a DWIM compiler? I'm pretty sure (happy to be corrected) pointer <-> integer conversions are implementation defined. Therefore casting between could perform some reversible operation that ensured round tripping worked, but does not require that ptr(a - b) == a - b even though a == int(ptr(a)) holds.

That is not a "similar" implementation, and it's not in the "library". It exposes the OS/ABI level exception functionality (which C++ exceptions are also built atop of) to the compiler.

This article is pretty terrifying:

      #import <pthread.h>
      #import <stdlib.h>
      
      // Globals
      pthread_mutex_t *gLck;
      int gSum;

      int main (int argc, const char * argv[])
      {
          pthread_t *tFoo, *tBar;
          int tErr, tArgF, tArgB;
      
          // create the mutex construct
          tErr = pthread_mutex_init(gLck);

And this is why, any cache without an eviction policy and/or size limitation is bad (and memoization _is_ a cache). I shudder every time I see a "magical" memoization function whose interface is just

   memo function-to-memoize