How can I pass an arbitrary (unknown) number of p5.Part's to a p5.Score constructor?

milrob14

It looks like p5.Score requires you to pass a specified number of parts to its constructor:

var score = new p5.Score(a, b, c, a, b, c)

But I want to do something like this:

var arr = []; var array_of_parts = fill_array_with_parts(arr); **var score = new p5.Score(array_of_parts)**; score.start();

Where the parts are played in order that they appear in the array. Any ideas?

GoToLoop

It looks like p5.Score requires you to pass a specified number of parts to its constructor:

Nope... it says: "p5.Part: One or multiple parts, to be played in sequence."
That is, we can pass as many p5.Part arguments as we want to!

However, if those p5.Part objects are stored within an array, we can call apply() in order to pass them as parts[0], parts[1], etc.: https://developer.Mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

const score = new p5.Score.apply(null, myParts);

Warning: Not tested! ~:>

milrob14

Yeah I tried that but got this error:

"Uncaught TypeError: function apply() { [native code] } is not a constructor"

Think I may just have to extend the constructor to take an array as an argument

Chrisir

You could for - loop over the array and pass only 1 or 5 each time (the last bits you need to do manually though)

GoToLoop

Seems like the operator new doesn't work straight w/ apply(): #-o
http://StackOverflow.com/questions/1606797/use-of-apply-with-new-operator-is-this-possible

If I understood correctly the 1st answers from StackOverflow, a possible solution is to call apply() over Function.bind. We also need to concat() [null] as the 1st element of the passed array argument:

const score = new ( Function.bind.apply(p5.Score, [null].concat(myParts)) );

GoToLoop

Of course life would be easier if you manage to convince "p5.Sound" library's developers to include an overloaded constructor for p5.Score class, so it accepts an array parameter too: :P

https://GitHub.com/processing/p5.js-sound/issues

If you do so, don't forget to mention this forum thread there so they have a better idea why you'd want the extra feature. :-\"

milrob14

Thanks for the clever solution!