Tersible

type Tersible<T = unknown> = T & {
  tersify(this: T, options?: Partial<TersifyOptions>): string
}

Tersible<T> is T plus a tersify() method. Any value of this shape controls its own output: tersify() calls the method instead of applying the default rules, unless raw: true is set.

The method receives the options the caller passed, so an implementation can honour maxLength. Nothing enforces the cap on the value you return.

Producing one

• tersible(subject, tersify?) returns Tersible<T> by defining the method on an existing value.
• Tersiblized(Base, tersify) returns a subclass whose instances have the method.
• Declaring tersify() on your own class satisfies the shape with no helper at all.

class Point {
  constructor(
    public x: number,
    public y: number
  ) {}
  tersify() {
    return `Point(${this.x}, ${this.y})`
  }
}

Using it in a signature

import type { Tersible } from 'tersify'

function log(value: Tersible) {
  console.info(value.tersify({ maxLength: 80 }))
}

Tersible defaults its parameter to unknown, so the bare form accepts any self-formatting value.

See Custom output for the guide.