Concept: Signals -- a simple mechanism for communcating with the environment

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The idea: a fixed set of stateless blocks that get run in response to lifecycle events.

import my_lib;

resource resource1: my_lib.Resource(id, "path/to/some/large/image.png");
resource resource2: my_lib.Resource(id, "path/to/some/complex/image.svg");
resource resource3: my_lib.Resource(id, "path/to/some/complex/image.svg");

when load {
   reset();
   resource1.load();
   resource2.load();
   // oops we forgot to load resource3
   // how do we handle this?
};

when exit {
   resource1.drop();
   // oops we for got to resource2.drop();
   // how do we handle this?
};

when error (err)  {
  my_lib.panic("Houston, we have a problem", err)
};

Questions:

• where can these appear?
• can they be in libraries, or is this a problem?
• maybe resources can nest an when load and when exit inside their constructor, so that the details are hidden.
• bike sheding about syntax. are these keywords?
• should they be extendable by embedding applications?