So, I've been writing Go for some years now, and while I know there is more to the for loop than the "usual" day-to-day case, this, I just don't quite get what is going on.

I mean, I can use it, but I don't get it.

for key, _, ok := it.Next(); ok; key, _, ok = it.Next()

It is from the immutable radix tree package here: https://github.com/hashicorp/go-immutable-radix.

I actually ask, because to retrieve the data I put in the tree, I have altered the code slightly () _ to blob), but now I am not sure if I should do the same in the second part.

for key, blob, ok := it.Next(); ok; key, _, ok = it.Next()

CodePudding user response：

The loop starts with calling it.Next(), and continues as long as ok is true. ok is reset with it.Next() at the end of every loop. At each iteration, the loop also sets key.

Your modification sets blob at the initialization, but it never sets blob again. For all iterations, blob will have the first value it got from it.Next(). It is likely that you should set blob at the last condition of the loop as well, so you can get the blob for the next element.