Data::Grove::Visitor man page on HP-UX

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Data::Grove::Visitor(3User Contributed Perl DocumentatiData::Grove::Visitor(3)

       Data::Grove::Visitor - add visitor/callback methods to Data::Grove

	use Data::Grove::Visitor;

	@results = $object->accept ($visitor, ...);
	@results = $object->accept_name ($visitor, ...);
	@results = $object->children_accept ($visitor, ...);
	@results = $object->children_accept_name ($visitor, ...);

       Data::Grove::Visitor adds visitor methods (callbacks) to Data::Grove
       objects.	 A ``visitor'' is a class (a package) you write that has meth‐
       ods (subs) corresponding to the objects in the classes being visited.
       You use the visitor methods by creating an instance of your visitor
       class, and then calling `"accept($my_visitor)"' on the top-most object
       you want to visit, that object will in turn call your visitor back with
       `"visit_OBJECT"', where OBJECT is the type of object.

       There are several forms of `"accept"'.  Simply calling `"accept"' calls
       your package back using the object type of the object you are visiting.
       Calling `"accept_name"' on an element object calls you back with
       `"visit_name_NAME"' where NAME is the tag name of the element, on all
       other objects it's as if you called `"accept"'.

       All of the forms of `"accept"' return a concatenated list of the result
       of all `"visit"' methods.

       `"children_accept"' calls `"accept"' on each of the children of the
       element.	 This is generally used in element callbacks to recurse down
       into the element's children, you don't need to get the element's con‐
       tents and call `"accept"' on each item.	`"children_accept_name"' does
       the same but calling `"accept_name"' on each of the children.
       `"attr_accept"' calls `"accept"' on each of the objects in the named

       Refer to the documentation of the classes you are visiting (XML::Grove,
       etc.) for the type names (`"element"', `"document"', etc.) of the
       objects it implements.

       The hash keys `"Contents"' and `"Name"' are used to indicate objects
       with children (for `"children_accept"') and named objects (for

       These are random ideas that haven't been implemented yet:

       ·   Several objects fall into subclasses, or you may want to be able to
	   subclass a visited object and still be able to tell the difference.
	   In SGML::Grove I had used the package name in the callback
	   (`"visit_SGML_Element"') instead of a generic name (`"visit_ele‐
	   ment"').  The idea here would be to try calling `"visit_PACKAGE"'
	   with the most specific class first, then try superclasses, and
	   lastly to try the generic.

       Ken MacLeod,

       perl(1), Data::Grove

       Extensible Markup Language (XML) <>

perl v5.8.8			  2003-10-21	       Data::Grove::Visitor(3)

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