Flow: Support private methods

[vjpr]

https://github.com/tc39/proposal-private-methods

[hadnet]

Any update about this? When trying to use private methods ( #myFunction(){} ) I got this warning: Classes may not have private methods. I'm using Flow 0.93.

[jml6m]

I'm interested in this feature as well. I have classes that extend other classes and using the typical ES6 approaches to "private" attributes/methods (like #, WeakMap, Symbols, etc.) just don't work out in my architecture. If flowtype handled this itself, it would be much easier (which means possibly adding a "protected" modifier as well)

[goodmind]

@jml6m I think TypeScript better suits your use case, Flow wouldn't add protected, because it isn't standard js

[sakarit]

@jml6m I think TypeScript better suits your use case, Flow wouldn't add protected, because it isn't standard js

Private methods is already in stage 3 so it will be standard soon.

[Ephys]

Private methods is already in stage 3 so it will be standard soon.

They meant that "protected" class fields isn't standard JS :)

[nnmrts]

Any news on this? Why is every second issue in this repository dead since end 2019? Why is there no global setting to suppress specific errors?

[sepehr]

This is the main reason we're trying to migrate to typescript. I wish I could help here.

[hadnet]

So jul 30 2020. Any news on this issue?

[XedinUnknown]

Yes, please! Since private properties already work, it should be trivial to add support for private methods as well. And this is already Stage 3 standard, as is mentioned above, so there's no reason to not do it.

[XedinUnknown]

Meanwhile, one way to go around it is to simply use interfaces.

interface Greeter
{
    getGreeting(): string
}

class MyGreeter implements Greeter
{
    getGreeting(): string
    {
        return 'Hello, ' + this.getName() + '!'
    }

    #getName(): string
    {
        return 'World'
    }
}

function greet(greeter: Greeter): void
{
    console.log(greeter.greet());
}

let greeter = new MyGreeter()
greet(greeter)

The function greet() doesn't know that greeter is an instance of MyGreeter; all it knows is that it's a Greeter. This is DIP, and I do this anyway in all my code.

[mischnic]

Another workaround is treating it like a property (assigning it) and then using .call

class Foo {
    #priv: (number) => string;

    constructor(){
        this.#priv = (a) => String(a);
    }

    run(){
        console.log(this.#priv.call(this, 123));
    }
}