go的链式方法

func (r *Request) Name(resourceName string) *Request {
    if r.err != nil {
       return r
    }
    if len(resourceName) == 0 {
       r.err = fmt.Errorf("resource name may not be empty")
       return r
    }
    if len(r.resourceName) != 0 {
       r.err = fmt.Errorf("resource name already set to %q, cannot change to %q", r.resourceName, resourceName)
       return r
    }
    if msgs := IsValidPathSegmentName(resourceName); len(msgs) != 0 {
       r.err = fmt.Errorf("invalid resource name %q: %v", resourceName, msgs)
       return r
    }
    r.resourceName = resourceName
    return r
}

// Namespace applies the namespace scope to a request (<resource>/[ns/<namespace>/]<name>)
func (r *Request) Namespace(namespace string) *Request {
    if r.err != nil {
       return r
    }
    if r.namespaceSet {
       r.err = fmt.Errorf("namespace already set to %q, cannot change to %q", r.namespace, namespace)
       return r
    }
    if msgs := IsValidPathSegmentName(namespace); len(msgs) != 0 {
       r.err = fmt.Errorf("invalid namespace %q: %v", namespace, msgs)
       return r
    }
    r.namespaceSet = true
    r.namespace = namespace
    return r
}

// NamespaceIfScoped is a convenience function to set a namespace if scoped is true
func (r *Request) NamespaceIfScoped(namespace string, scoped bool) *Request {
    if scoped {
       return r.Namespace(namespace)
    }
    return r
}

// AbsPath overwrites an existing path with the segments provided. Trailing slashes are preserved
// when a single segment is passed.
func (r *Request) AbsPath(segments ...string) *Request {
    if r.err != nil {
       return r
    }
    r.pathPrefix = path.Join(r.c.base.Path, path.Join(segments...))
    if len(segments) == 1 && (len(r.c.base.Path) > 1 || len(segments[0]) > 1) && strings.HasSuffix(segments[0], "/") {
       // preserve any trailing slashes for legacy behavior
       r.pathPrefix += "/"
    }
    return r
}