Make closure replacement dynamic

[aitrusgit]

Right now you can freely overwrite a preexistent closure in rules-js by simply providing the overwrite flag

engine.add("closure-that-changes", definition, { overwrite: true });

Then when you invoke it directly you will exercise the modified behavior

engine.process("closure-that-change", fact);

However it won't affect preexistent higher order closures which are composed with "the-closure-that-changed".

engine.process("higher-order-closure", fact); // exercise old "closure-that-changes"!!! =(

[aitrusgit]

Just to clarify, the definition of "higher-order-closure" might be something like this

{
  "name": "higher-order-closure",
  "rules": [
      {
          "when": "always",
          "then": "closure-that-change"
      }
   ]
}

[aitrusgit]

We can achieve this behavior at parser level. Instead of creating composite closures with references to real composed closures we can add a level of indirection there. Something that abides to the Closure interface but delegates process into the real one.

Simpler solution will be doing a lookup in the closure registry every time for the real one. It might be not that efficient though (assuming we exercise the process logic way more times than what we change rules).

A more efficient solution will be to provide such indirection bound to the real closure and have a way to backtrace them and change the binding every time a closure is replaced.