@Archie said:
But if a string player is playing portamento there wouldn't be an attack on the second note. I'm not sure what you're trying to achieve. If you're trying to get the most natural sound then you don't want an attack on the second note, you just want the sound of the first note sliding to the second in one fluid bow movement. I'm confused by what you mean when you say "there is no matching attack on the second note".
I'm not sure that is quite accurate. I'm not a violinist but I do think at the top of the slide, you can either increase the bow pressure or change bow. I'm not saying the attack needs to be loud but I certainly want to hear the note you are sliding into pretty clearly, else you are "sliding into oblivion".
One way of dealing with this problem, I suppose, would be to reduce the volume or expression controller level on the slide and increase it when you want the upper note to be heard.