Rule: no-watch

[binjospookie]

Watch have last computation priority.

Frequent use of the watch can lead to races that are very difficult to debug. Often, the use of the watch can be avoided (by using target, for example).

[igorkamyshev]

But effects has the same computation priority 🤔

I agree, we can forbid .watch because it leads to imperative code, but I cannot find the connection with computation priority.

[binjospookie]

but I cannot find the connection with computation priority

forward({
  from: fooEvt,
  to: barEvt
});

fooEvt.watch(barEvt);

The second option can lead to an "unexpected" calculation order.

[binjospookie]

If u want I can try to implement this rule. Both my issues are not "do it for us" :)

I just need an approve of the idea so I don't waste my time.

[igorkamyshev]

So, I agree, it's a good rule. Let's do it. I think we ought to mark this rule as warn.

[binjospookie]

Maybe u can give me some recommendations how to write new rule? I wrote rules many-many years ago :c

[igorkamyshev]

Oh, I don't think so 🥲 my only advice: try to write as many tests as you can. ESLint plug-in documentation is a really poor.

[binjospookie]

Need a little help. What we should to do with the JS way branch? .watch can be called in a file that does not declare a watchable unit. We can't rely on unit naming, because there is no naming convention for events.

[igorkamyshev]

Such a good question. I don't have an answer for you.

Maybe, we ought to introduce #32 before?

But, it isn't resolving a problem with something like sample(...).watch(...) and so on. So, we have to use some heuristics to detect method calls.

So, in my opinion, we have three ways:

1. Specify this rule only for TS-code
2. Don't make this rule
3. Use heuristics and name convention to detect watchers

What do you think?

[binjospookie]

I like the first way. I'll explain why.

Don't take the rule away from developers with TypeScript and Effector projects just because not all projects have TypeScript.

Binding to the name convention seems fragile because any naming rule can be disabled.

[igorkamyshev]

I agree. But we should notice it in documentation.