Shorthand singleton marks

[mbostock]

For single-instance marks, it’d be neat if you could just pass options without data. For example:

Plot.text({
  text: "Hello, world!"
  x: new Date("2016-05-01"),
  y: 100,
  dx: -10,
  dy: 40,
  frameAnchor: "top-left"
})

Could be equivalent to:

Plot.text({length: 1}, {
  text: ["Hello, world!"],
  x: [new Date("2016-05-01")],
  y: [100],
  dx: -10,
  dy: 40,
  frameAnchor: "top-left"
})

It feels like the helper would need to know which options possibly represent channels, though. And there would potentially be ambiguity with alternative representations of data (such as Arquero objects #449); though that could be addressed by checking the number of arguments and whether the first is a plain object (Object.getPrototypeOf === Object.prototype).

[mbostock]

Possible approach, but I’m unsure how to generalize…

export function text(data, options = {}) {
  if (arguments.length === 1 && Object.getPrototypeOf(data) === Object.prototype) {
    const {x, y, text, ...rest} = data;
    data = {length: 1};
    options = {...rest, x: x == null ? x : [x], y: y == null ? y : [y], text: text == null ? text : [text]};
  }
  const {x, y, ...rest} = options;
  if (options.frameAnchor === undefined) ([x, y] = maybeTuple(x, y));
  return new Text(data, {...rest, x, y});
}