Example

FilterMethods myfilter_methods = FILTER_METHODS_INITIALIZER;const Filter
 *myfilter;int myfilter_insert(FilterLayer *layer, pblock *pb)
{if (pblock_findval("dont-insert-filter", pb))        
return REQ_NOACTION;return REQ_PROCEED;}...myfilter_methods.insert = &myfilter_insert;
myfilter = filter_create("myfilter", &myfilter_methods);...