Callback source

Creates a pull-style source that retrieves observations by calling an R function. The callback must return either NULL when no observation is available or an observation compatible with the online observation contract. In practice this means a scalar, a one-row data.frame, or a list containing at least a value field and optionally idx, timestamp, and payload.

Usage

har_source_callback(poll_fn, name = "callback")

Arguments

poll_fn

Function called to request the next observation.

name

Source name.

Value

A har_source_callback object.