Cannot read property: _in_call_that_will_be_reverted

[km19809]

Description

tangle/tangle_ts/src/tangle.ts

Lines 92 to 97 in 9abd443

	moduleImports[importName] = function (...args: any) {
	const r = importValue(...args);
	// This call will be reverted so it's OK if it causes a temporary desync.
	if (this._in_call_that_will_be_reverted) {
	return r;
	}

When I call imported JS functions, this becomes undefined.
So, this._in_call_that_will_be_reverted cannot be read.

What I did
I ran the example counter but in Zig instead of AssemblyScript.

my_wasm.zig

var num: f64 = 0.0;

extern fn report_number_change(n: f64) void;

export fn increment( val: f64) void{
    num += val;
    report_number_change(num);
}

export fn multiply( val: f64) void{
    num *= val;
    report_number_change(num);
}

However, I doubt that is a Zig-related problem.
As I know, the value of the this keyword depends on its context.
Then, what is the value of this, if I call a function in a WASM?

To check that, I modified tangle.js:

              const r = importValue(...args);
              console.warn(`${importName}():${this}`)
              if (this?._in_call_that_will_be_reverted) {
                return r;
              }

Then it says:

The first 4 calls are exports.increment(1)s, and others are exports.multiply.callAndRevert(3)s.

This shows that wrapping a function call did not help!

tangle/tangle_ts/src/tangle.ts

Lines 328 to 331 in 9abd443

	wrapped_function.callAndRevert = (...args: any) => {
	this._in_call_that_will_be_reverted = true;
	this.call_and_revert(key, ...args);
	this._in_call_that_will_be_reverted = false;

Additional note
I tried an arrow function, but it made this._in_call_that_will_be_reverted undefined, and this was not a Tangle instance. (it was a function.)
moduleImports[importName] = (...args) => {
I want to figure out why this happens, but the keyword this was nearly impossible to search.

[km19809]

Ok, things get complicated.
We want this to be an instance of Tangle. It is easy to solve: we can use bind(tangle).
However, instantiation of Tangle needs a time_machine instance.
Because time_machine.setup instantiate the WASM binary, we need to modify imported functions before the setup.
It is something like the chicken-egg problem.
For now, we are trying to access a property of an uninitialized instance.
It is hard to solve...

[DiogoNeves]

Maybe I misunderstood the issue. When is the function containing _in_call_that_will_be_reverted called? If you bind, it should still have access to the time_machine once it's set?
Options I'm thinking:

• do not require the time_machine in the constructor, although this makes it temporarily unsafe?
• bind the importObjects from Time Machine in the Tangle constructor (makes Time Machine only assignable to 1 instance)
• create a 3rd object with the references it needs and use it after everything is setup?

I'm sure there are better solutions, I'm just curious what would help :)

[km19809]

The function containing _in_call_that_will_be_reverted is called when I call an imported function.
In addition, the function does not need a time_machine instance.
I prefer your 3rd option, but I am not sure.