chickadee » augeas » aug-defnode

aug-defnode a name expr valueprocedure

If the node at EXPR does not exist, creates a node at EXPR with value VALUE, storing the node in variable NAME. This is like using defvar followed by aug-set!.

If the node or nodes at EXPR do exist, stores the corresponding nodeset in variable NAME. The node values are not modified and VALUE is ignored.

Returns two values: the integer number of nodes in the nodeset, and a boolean indicating whether a node was created or not.

A typical use is with the XPath predicate [last()+1] to append a node to a list of nodes that all have the same name, and keep a reference to the new node.


;; First create a new node with a value and assign it to a variable;
;; then assign the same node to a second variable (value is ignored).
(aug-defnode a "myalias" "/files/etc/hosts/1/alias[last()+1]" "crichton")
 ;=> values: 1 #t
(aug-defnode a "myalias1" "/files/etc/hosts/1/alias[last()]" "crichton2")
 ;=> values: 1 #f
(aug-get a "$myalias") 
 ;=> "crichton"
(aug-get a "$myalias1")
 ;=> "crichton"