Promise-based execution with halting.

Requires native support for Promise, class, const and let.

This module is no longer maintained.

npm install eh

Creates a new execution, to be performed by executor. Each execution has a .promise property containing a promise for when it is completed. The executor is called with resolve and reject arguments to either fulfill or reject this promise.

The executor may return a function ("halt handler") which will be called when execution is to be halted. It'll only be called once, and only if the .promise is still pending. How execution is halted, if at all, is left to the executor. The executor may chose to fulfill or reject the promise, or leave it pending.

Note that if the executor calls resolve() with another pending promise its halt handler may still be called until that promise settles. And since promise state cannot be observed synchronously race conditions may occur where the halt handler is called after resolving the promise, but before that change could be observed.

Each execution has a .halted property containing a promise for when it is halted. This may never happen, in which case the promise will never settle.

Executions can be halted by calling .halt(). If the executor did not return a halt handler, or the .promise has already (been observed to have) settled, the .halted promise is fulfilled with false. If the halt handler throws an error that error is used to reject the .halted promise. Otherwise the .halted promise is fulfilled with true. The .halted promise is returned when calling .halt().

Note that even if the .halted promise is fulfilled with true the .promise may still settle.

Halts the execution after the delay, specified in milliseconds. setTimeout is used internally. Consequently the execution may be halted a little sooner or a little later than specified.

Returns an object with a .halted property, containing the .halted property of the execution. Additionally the handle returned by setTimeout is available on the returned object as .timer. In io.js you could call unref() on the timer so it won't unnecessarily keep the program running. This may have performance implications, please read the io.js documentation carefully.

Returns an object with a new Eh constructor, which uses the value of Promise to construct the .promise and .halted promises. This lets you use eh with non-native Promise implementations.

ISC