このページはまだ翻訳されていないため、英語で表示されます。 翻訳に参加する

RxDart vs FxDart › #42 · One call every 100 ms

One call every 100 ms

Toss-up async

• fx
• toAsync
• map

Requirement

Send five pings to a rate-limited endpoint, each starting at least 100 ms after the previous one. Record every call's start on a monotonic Stopwatch, print the five responses, and print spaced: true only if all gaps respected the limit. Both versions must print the lines shown under Expected output.

pong #1
pong #2
pong #3
pong #4
pong #5
spaced: true

Side by side

Why they differ

Pacing is about time, so you might expect the stream to win — and RxDart does have the word for it: interval holds each event back 100 ms before it reaches the ping, and backpressure keeps the whole thing sequential. One operator, requirement met.

But a pull pipeline is sequential by default, and that turns pacing into something almost embarrassingly simple: put the delay inside the mapper. Each pull waits 100 ms, then calls — the next pull cannot begin until this one finishes, so the spacing is structural, no operator needed. The Stopwatch check prints spaced: true on both sides. Call it a tie with a caveat each way: RxDart names the concept explicitly, which reads better in a pipeline full of other time operators; FxDart gets it as a one-line consequence of demand, but only because this task wants strictly serial calls — for spacing events that arrive on their own schedule (a real event stream), reach for the stream side of the bridge (fxStream) and RxDart's time vocabulary.