Imperatively push events into a Stream.
npm install --save most @most/create
create :: (Error e) ⇒ Publisher a b e → Stream
Publisher :: (Error e) ⇒ ((a → void) → (b → void) → (e → void)) → (void → void)
Create a push-stream for imperatively pushing events, primarily for situations where declarative sources can't be used.
The publisher function receives 3 functions as arguments, which it can use to publish events, end the stream, or signal an error. It may return a dispose function. The dispose function will be called once all consumers have lost interest in the stream, and should free any resources held by the publisher.
Note that the publisher will not be called until there is demand for the stream's events. Specifically, the publisher will be called when the number of observers goes from zero to one. Likewise, the dispose function will be called when the number of observers again returns to zero. The publisher would then be called again if the number of observers subsequently goes from zero to one, and so on.
add, end, and error
The publisher function can use
xto the stream
end()- End the stream. Any later calls to
errorwill be no-ops.
error(e)- Signal that the stream has failed and cannot produce more events.
If you never call
error, the stream will never end, and consumers will wait forever for additional events.
errorfunctions out of the publisher closure is not supported.
// Unsupported:let emitEvent emitEnd emitErrorconst stream = most
If the publisher returns a dispose function, it will be called when the stream ends or errors--for example, when the publisher explicitly calls
error, or when all consumers lose interest.
dispose- free resources held by the publisher
Note that if the stream neither ends nor fails, the dispose function will never be called.
end to push events and then end the stream.
// Add events and then endconst stream =// Logs// 'event 1' after 1 second// 'event 2' after 3 seconds// 'event 3' after 10 seconds// 'dispose' after 10 secondsstream;
error to fail the stream and propagate an Error:
// Add events and then failconst stream =;// Logs// 'event 1' after 1 second// '[Error: oops!]' after 3 secondsstream; // Catch the error as a promise