Cyrille is doing it one go by exploiting the "bang" feature of switch~ with an [until] loop to basically "fast forward" the zeroing process by however many blocks long the buffer is. It's really clever, and I don't think it screws anything up on the outside. This is a technique I'd never thought of, and I can imagine some interesting things coming from this (though I'm not sure it's a canonical technique or incidental). There are some things to think about, like whether the [inlet~] vector is cleared or if it just keeps the last 64 samples for each iteration of the [until] loop.
I'm just talking in general about the idea of amortizing the cost of the operation across multiple blocks, which I assume is what's happening in his abstraction (or at least what's supposed to happen). Hm... In practice, how do you find Pd-l2ork's "clear" method compares to Cyrille's abstraction?
-Jonathan