What motivates the complicated dance for NewPromiseCapability?

[domenic]

@allenwb, would appreciate your help on this.

Back in https://github.com/domenic/promises-unwrapping/tree/a3a8a88c9091a009be7d2320cf0e590317db5956, we had a very simple GetDeferred + Deferred Construction Functions pair. Now we have a complicated dance involving NewPromiseCapability, CreatePromiseCapabilityRecord, and GetCapabilitiesExecutor Functions, each of which is much longer than either of their previous counterparts, and all of which contain extensive invariant checks and tricks.

To make matters worse, from what I can tell the checks introduced there are at the root of the problems @cscott is experiencing with bugs like #94 and #95.

What have we gained with the new system, and can you see a way of fixing it to fix those bugs? I would much rather just revert to the old system if that's possible.

[domenic]

Ping @allenwb

[domenic]

Assigning back to me. Action item: figure out what, if any, observable differences there are between the previous version and the current one. That will help resolve #94 and #95.