The go-iterators project is a library offering the iterator pattern for Golang.
Why iterators are useful?
- They can be lazy and the data will be fetched just when needed.
- They fit a lots of use cases. From a simple slice iteration to data transformation to tree traversals.
Creating an iterator is as simple as defining a function, the function will have to compute the next item in the iteration.
iter := NewDefaultIterator(func() (next interface{}, eod bool, err error) {
// Here put the logic that is computing the next element.
// 1. If there is a next element return: next, false, nil
// 2. If an error occurs computing the next element return: nil, false, error
// 3. If there is no next element return: nil, true, nil
})
defer iter.Close()func FisIterator(fis []os.FileInfo) iterator.Iterator {
i := 0
return iterator.NewDefaultIterator(func() (interface{}, bool, error) {
if i >= len(fis) {
return nil, true, nil
}
file := &fis[i]
i++
return file, false, nil
})
}