Formatted-callback-sink-type

FormattedCallbackSink is the public callback sink type used for formatter-driven text delivery. It is the concrete sink type returned by both formatted_callback_sink(...) and text_callback_sink(...), and it stores the rendering function and the string callback used for each record.

Interface

pub struct FormattedCallbackSink {
  formatter : RecordFormatter
  callback : (String) -> Unit
}

output

• FormattedCallbackSink - Public synchronous sink type that renders each record through a stored formatter and forwards the text to a stored callback.

Explanation

Detailed rules explaining key parameters and behaviors

• This is a public root struct, not a type alias.
• The current fields are formatter : RecordFormatter and callback : (String) -> Unit.
• formatted_callback_sink(...) constructs this type directly from a formatter function and string callback.
• text_callback_sink(...) also returns this same type after adapting a TextFormatter into a RecordFormatter.

How to Use

Here are some specific examples provided.

When Need A Typed Formatter-driven Callback Sink Value

When code should keep the concrete rendered-text callback sink type visible:

let sink : FormattedCallbackSink = formatted_callback_sink(fn(rec) { rec.message }, fn(line) { println(line) })

In this example, the sink value stays explicit and preserves the formatter-driven text delivery path.

When Need A Typed Text-callback Logger

When logging should preserve the rendered-text callback sink type in the logger:

let logger : Logger[FormattedCallbackSink] = Logger::new(
  text_callback_sink(text_formatter(show_timestamp=false), fn(line) { println(line) }),
)

In this example, the concrete formatted callback sink remains part of the logger type.

Error Case

e.g.:

• FormattedCallbackSink itself does not have a runtime failure mode.

• Output readability, callback behavior, and runtime cost still depend on the stored formatter and callback functions.

Notes

1. Use formatted_callback_sink(...) or text_callback_sink(...) when you need a value of this type.

2. Use CallbackSink when the destination should receive full Record values instead of rendered text.