I'm writing a webdav server (it works, yay!), but now I'm looking at polishing the edges before I release. A webdav server, for those who aren't up on their jargon, is a HTTP fileserver. One of the things I have observed is that good clients will update the screen as the information flows in (in XML). Now naturally I did the code in good procedural style - one routine gets the list of files, another builds the XML. But this means I build the entire XML document before I send it - leading to the feeling of slowness on the client side.

The meta-code looks like this:

PROPFIND {
 get_properties_recursive{
  while properties
   get_property_nonrec
   generate_xml_chunkette
  loop
  return xml_chunks
 }

 add_xml_header_and_footer
 return xml_document
}

[download]

There are obvious things I could do, like pass in the HTTP::Daemon object, and print each chunk as I generate it. But this breaches functional and procedural coding guidlines as I understand them. I will have duplicated server output routines, and my code will not be obvious.

A while ago I heard about something called continuations, which perl doesn't have, but they sound ideal. My current plan is to completely turn my routines inside out (ouch), and hand a code ref to HTTP::Daemon, which it will then call for each chunk of XML (functional style). This will require messy state switches and other yick. Before I do this, would anyone care to recommend a better approach?

____________________
Jeremy
I didn't believe in evil until I dated it.

In reply to Turning a sub inside out by jepri

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