trace variables

[aplicacionamedida]

Trace variables: A function is called each time a variable is accessed or geted.

[vendethiel]

How do you implement that efficiently anyway?

[aplicacionamedida]

I think that the only solution is to declare a variable with this special property: to be traced. Perhaps the traced variable can be registered internally by the compiler and associate its corresponding callbacks in case of being geted or setted. The compiler adds after each access to a variable a call to the associated callback.

Probably the callbacks requires a reference to that variable to be passed as a parameter. This also means that the traced variable needs to be associated to an object , because local vars can't be passed by reference. For example the traced variable could be a property of an object dedicated to store traced variables.

This new feature could also be used to emulate the observer pattern.

[notslang]

JS already has getters and setters, so you could probably use that to do your variable tracing. Or you can track variables using the Blink DevTools/Node Inspector.

Though I think that the idea of making tracing a part of CoffeeScript is pretty far out of scope. It would break the "CoffeeScript is just JS" principle, because tracing is way more than just syntactical sugar for common idioms.

[GeoffreyBooth]

Closing as this proposal doesn’t appear to have consensus.