Haketilo

function Showable(on_show_cb, on_hide_cb) {

    this.shown = false;

    /*

     * Wrap the requested callback into one that only executes it if showable is

     * not shown.

     */

    this.when_hidden = cb => {

	const wrapped_cb = (...args) => {

	    if (!this.shown)

		return cb(...args);

	}

	return wrapped_cb;

    }

    this.show = () => {

	if (this.shown)

	    return false;

	this.shown = true;

	try {

	    on_show_cb();

	} catch(e) {

	    console.error(e);

	}

	return true;

    }

    this.hide = () => {

	if (!this.shown)

	    return false;

	this.shown = false;

	try {

	    on_hide_cb();

	} catch(e) {

	    console.error(e);

	}

	return true;

    }

}

#EXPORT Showable