Custom getters and setters in C/C++

[sazlang]

Is there any way to bind getter and setter for JS variable from C? Something like that.

int myVariable = 0;

int myVariableGetter() { return myVariable; }
void myVariableSetter(int v) { myVariable = v; }

int main() {
  ...
  duk_bind_getter_for("myVariable", myVariableGetter);
  duk_bind_setter_for("myVariable", myVariableSetter);
  duk_eval_string(ctx, "myVariable = 5;");
}

[svaarala]

Yes, you can use https://duktape.org/api.html#duk_def_prop.

It works similarly to Object.defineProperty() but takes the getter/setter argument via the value stack, see the API documentation for examples.

[sazlang]

Hmm. Thanks. But what about capturing setters/getters for all dynamic properties of JS object?

[svaarala]

What dynamic properties do you mean?

[svaarala]

Do you mean capturing all property accesses, regardless of property name? If so, getters/setters don't allow you to do that, but you can use a Proxy object for that.

[sazlang]

Yes, I mean. I will look for Proxy object.

[svaarala]

There are some Ecmascript-based Proxy examples here: https://wiki.duktape.org/HowtoVirtualProperties.html. The C API call for creating a Proxy is https://duktape.org/api.html#duk_push_proxy if you'd rather initialize the Proxy from C code.

[svaarala]

Proxy is a generic Ecmascript concept so almost any Proxy tutorial should be usable. Duktape doesn't implement all traps yet, but get, set, has, delete are probably what you need and they are implemented.

[svaarala]

@sazlang Any updates or ready to close?