Quadrille.factory

Tags a function so that fill runs it once per cell and stores what it returns, instead of storing the function itself as that cell's display routine.

A function value in a quadrille is normally a display function: it is called at draw time with the cell's drawing parameters. A function that produces a value has no way to say so, and no amount of introspection can tell the two apart — so the tag is explicit. Quadrille.factory(fn) marks the function in place (fn._isFactory = true) and returns it; a non-function comes back unchanged.

Example

Note

The factory receives { row, col } — enough to make a fresh object, a varied tile, or a value that depends on position. The same tag makes the value argument of createQuadrille and fill produce per-cell values; see createQuadrille(width, height, predicate, value) for the predicate form, which decides which cells are filled rather than what they hold.