# tmuxq.ExactlyOne

- **Module:** tmuxq
- **Package:** github.com/libtmux/libtmux-go/tmux
- **Language:** Go
- **Kind:** function
- **Source:** https://github.com/libtmux/libtmux-go/blob/52968a3181c1c9e6d1b26c565d4b170968ae61c0/tmuxq/query.go#L53
- **Page:** https://libtmux.org/en/go/latest/reference/tmuxq-exactlyone/

```
tmuxq.ExactlyOne(values: []T, predicate: func(*T) bool) -> (T, error)
```

ExactlyOne returns a shallow copy when exactly one source-ordered value is accepted by predicate. It examines values until source exhaustion confirms a sole match, or stops at the second match. It returns the zero value of T with [ErrNoMatch] for no matches or [ErrMultipleMatches] for multiple matches; callers can classify either error with [errors.Is].