Base blocktype methods for exporting blockinstance config.

This feeds into the View export. Blocktypes can export all the
information they need to be imported again.
Signed-off-by: Nigel McNie <nigel@catalyst.net.nz>

htdocs/blocktype/lib.php

@@ -275,6 +275,38 @@ abstract class PluginBlocktype extends Plugin {
         return true;
     }
 
+    /**
+     * Given a block instance, returns a hash with enough information so that 
+     * we could reconstruct it if given this information again.
+     *
+     * Import/Export routines can serialise this information appropriately, and 
+     * unserialise it on the way back in, where it is passed to {@link 
+     * import_create_blockinstance()} for creation of a new block instance.
+     *
+     * @param BlockInstance $bi The block instance to export config for
+     * @return array The configuration required to import the block again later
+     */
+    public static function export_blockinstance_config(BlockInstance $bi) {
+        // TODO: a default implementation might just turn $bi->get('configdata') into an array
+        return array();
+    }
+
+    /**
+     * Creates a block instance from a given configuration.
+     *
+     * The configuration is whatever was generated by {@link 
+     * export_blockinstance_config()}. This method doesn't have to worry about 
+     * setting the block title, or the position in the View.
+     *
+     * @param array $config The config to use to create the blockinstance
+     * @return BlockInstance The new block instance
+     */
+    public static function import_create_blockinstance(array $config) {
+        // TODO: a default implementation might just create a new blockinstance 
+        // with the config shunted into configdata - but with artefactids 
+        // replaced with new ones
+    }
+
 }
 
 abstract class SystemBlockType extends PluginBlockType {