package uio

import "io"

// Cycler stores any io.Closer. When the value is replaced, the old value is
// closed.
type Cycler struct {
	value io.Closer
}

// Value returns the value of the Cycler. If there is no value, nil is returned.
func (this *Cycler) Value () io.Closer {
	return this.value
}

// Set replaces the value of the Cycler, closing the previous one if it exists.
func (this *Cycler) Set (value io.Closer) error {
	err := this.value.Close()
	this.value = value
	return err
}

// Close closes the Cycler's value early. It will be set to nil.
func (this *Cycler) Close () error {
	return this.Set(nil)
}