style(typings): Use typeof to capture typings for all static Observab…

[david-driscoll]

…le methods

[david-driscoll]

This pulls out the static methods as per the discussion in #870

[kwonoj]

As already discussed in original PR, I like this changes and this looks good to me. Thanks for taking time with effort @david-driscoll :)

I'll check in this once @Blesh agrees.

[david-driscoll]

I've also gone and rebased the other branches to be based on this one, so the changes should disappear from those PRs once this is merged.

[luisgabriel]

Super cool! 👍

[kwonoj]

It's off-topic question, is this applicable to non-static instance also?

[david-driscoll]

Unfortunately no, because there is no way to consider the type of this currently with TypeScript.

Consider:

export function combineLatest<T2>(second: Observable<T2>): Observable<[T, T2]>;

With this function we have no idea what T is, so to define it properly we have to replace it with any to compile.

export function combineLatest<T2>(second: Observable<T2>): Observable<[any, T2]>;

And then we loose our type information. #870 works around this, copying the definitions from the operator, defined as a function, and strips out any references to T from the function declaration.

The typinggen.js basically converts:

export function combineLatest<T, T2>(second: Observable<T2>): Observable<[T, T2]>;

to:

interface Observable<T> {
    combineLatest<T2>(second: Observable<T2>): Observable<[T, T2]>;
}

So then we can then use typeof operator.xyz, as seen in #871.

[kwonoj]

Make quite sense, thanks. Think this topic need to be continued under original PR.

[kwonoj]

@david-driscoll Would you able to align commit message start with lowercase as same as other commit history?

[kwonoj]

Otherwise, change looks cool to me. I'll let this opened for a while to have any other suggestions / opinions around after commit message's aligned. Expecting to take some time due to holiday.

[benlesh]

Merged with d4dd7f1. Thanks @david-driscoll!

[lock]

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