https://github.com/Workiva/go-datastructures/tree/master/bitarray中的“ s”在哪里定义？

Question

I do not see where s is defined. Guru will not tell me. All I get is "no object for identifier" but it knows about the k right beside it. Here is a snippet that is typical of the linked code:

func getIndexAndRemainder(k uint64) (uint64, uint64) {
    return k / s, k % s
}

The one letter variable name definitely makes it harder to grep around for. I have looked for the usual suspects: var s uint64, s := ..., and nothing. Clearly it needs to be a global value defined somewhere.

This leaves me with two questions:

1. Where is s coming from?
2. How would I find it without asking here?

EDIT: For others who stumble on this.

Guru failed me because I did not checkout the source for the package under a proper Go workspace by placing the git clone under /some/path/src and setting the GOPATH to /some/path. So while I thought GOPATH=. guru definition s would work, the GOPATH was ignored. guru could find k because it is in the file but it did not know how to look in other files.

My grep failed cause const uses a simple = not a :=. I will remember this when grepping in the future.

Answer 1

It is defined in go-datastructures/bitarray/block.go:

// s denotes the size of any element in the block array.
// For a block of uint64, s will be equal to 64
// For a block of uint32, s will be equal to 32
// and so on...
const s = uint64(unsafe.Sizeof(block(0)) * 8)

As the variable s was not defined in the function, and it was not prefixed by a package name or alias, it had to be a global (variable or constant) of the bitarray package.

Once that was known, I went through every file in the folder go-datastructures/bitarray that was not suffixed with _test and I looked for a top-level declaration for s.