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Ryan McKinley resolved SOLR-388. -------------------------------- Resolution: Duplicate Fix Version/s: 4.0 the types of thigns this issue points to are taken care of in SOLR-1566 > Refactor ResponseWriters and Friends. > ------------------------------------- > > Key: SOLR-388 > URL: https://issues.apache.org/jira/browse/SOLR-388 > Project: Solr > Issue Type: Improvement > Components: Response Writers > Affects Versions: 1.2 > Reporter: Luke Lu > Fix For: 4.0 > > > When developing custom request handlers, it's often necessary to create > corresponding response writers that extend existing ones. In our case, we > want to augment the result list (more attributes other than numFound, > maxScore, on the fly per doc attributes that are not fields etc.) , only to > find JSONWriter and friends are private to the package. We could copy the > whole thing and modify it, but it wouldn't take advantage of recent fixes > like Yonik's FastWriter changes without tedious manual intervention. I hope > that we can can *at least* extends it and overrides writeVal() to add a new > result type to call writeMyType. > Ideally the ResponseWriter hierarchy could be rewritten to take advantage of > a double dispatching trick to get rid of the ugly if something is instance of > someclass else ... list, as it clearly doesn't scale well with number of > types (_n_) and depth (_d_) of the writer hierarchy, as the complexity would > be O(_nd_), which worse than the O(1) double dispatching mechanism. Some > pseudo code here: > {code:title=SomeResponseWriter.java} > // a list of overloaded write method > public void write(SomeType t) { > // implementation > } > {code} > {code:title=ResponseWritable.java} > // an interface for objects that support the scheme > public interface ResponseWritable { > public abstract void write(ResponseWriter writer); > } > {code} > {code:title=SomeType.java} > // Sometype needs to implement the ResponseWritable interface > // to facilitate double dispatching > public void write(ResponseWriter writer) { > writer.write(this); > } > {code} > So when adding a new MyType and MySomeResponseWriter, we only need to add > these two files without having to muck with the writeVal if-then-else list. > Note, you still need to use the if else list for builtin types and any types > that you can't modify in the write(Object) method. > {code:title=MyType.java} > // implements the ResponseWritable interface > public write(ResponseWriter writer) { > writer.write(this); > } > {code} > {code:title=MySomeResponseWriter.java} > // only need to implement this method > public void write(MyType t) { > // implementation > } > {code} -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org