Lectures

We break down how to get a file or directory “passport” via os.Stat: what the os.FileInfo interface is, how to read basic metadata ( Name(), IsDir(), Size(), ModTime(), Mode()), how to handle file system errors via os.IsNotExist/ os.IsPermission, and how to apply this in practice (the inspect utility, checking storage in TaskBox, checking a “regular file” via IsRegular()).

We break down how to get a directory’s contents in Go with a single call using os.ReadDir, what exactly is inside []os.DirEntry, how the “lightweight” DirEntry differs from the full FileInfo, why e.Name() is not a path, how to build a path correctly with filepath.Join, and how to handle errors cleanly ( if err != nil, wrapping with fmt.Errorf using %w).

We break down how to traverse a file tree correctly in Go using filepath.WalkDir: how the fs.WalkDirFunc callback is structured, why it is important to check err, how to control traversal with filepath.SkipDir and SkipAll, and which practical measures help make directory scanning predictable and safe (including lexical validation of a user-supplied path using filepath.IsLocal).

We break down a practical pipeline “traverse → collect → filter → sort”: collect WalkDir results into []Item, write predicates based on strings.HasPrefix/ HasSuffix/ Contains, compose conditions via the Filter function, and then make output deterministic using sort.Slice and sort.SliceStable, including a tie-breaker (for example, by path).

We break down how to design error handling when recursively walking a file tree in Go using filepath.WalkDir: what the err parameter in the callback means, when to return a regular error and when to use filepath.SkipDir, how to collect “as much data as possible” and still not lose problems with errors.Join, and why wrapping via %w makes diagnostics and error classification (via errors.Is/ errors.As) genuinely convenient.