Special Support for OOP via Object Maps
See the pattern on [_Simulating Object-Oriented Programming_][OOP] for more details.
Object maps can be used to simulate object-oriented programming (OOP) by storing data as properties and methods as properties holding function pointers.
If an object map’s property holds a function pointer, the property can simply be called like a normal method in method-call syntax.
This is a short-hand to avoid the more verbose syntax of using the call
function keyword.
When a property holding a function pointer or a closure is called like a method, it is replaced as a method call on the object map itself.
let obj = #{
data: 40,
action: || this.data += x // 'action' holds a closure
};
obj.action(2); // calls the function pointer with 'this' bound to 'obj'
obj.call(obj.action, 2); // <- the above de-sugars to this
obj.data == 42;
// To achieve the above with normal function pointer call will fail.
fn do_action(map, x) { map.data += x; } // 'map' is a copy
obj.action = Fn("do_action");
obj.action.call(obj, 2); // a copy of 'obj' is passed by value
obj.data == 42; // 'obj.data' is not changed