Wednesday, July 18, 2007

Hackweek aftermath

Novell Hackweek left me with a last itch to scratch -- Cornelius' proposal of a Ycp To Ruby translator.

Earlier this year, I already added XML output to yast2-core which came in very handy for this project. Using the REXML stream listener to code the translator was the fun part of a couple of late night hacks.

The result is a complete syntax translator for all YaST client and module code. The generated Ruby code is nicely indented and passes the Ruby syntax checker.

Combined with Duncans Ruby-YCP bindings, translating ycp to Ruby should be quite useful as we try to provide support for more widespread scripting languages.

The translator is available at and requires a recent version of yast2-core, which supports XML output and the '-x' parameter of ycpc.
Then run
  ycpc -c -x file.ycp -o file.xml

to convert YCP code to XML.
Now use the xml-ruby translator as
  cd yxmlconv
  ruby src/converter.rb file.xml > file.rb

Translating e.g /usr/share/YaST2/modules/Arch.ycp

module "Arch";
// local variables
string _architecture = nil;
string _board_compatible = nil;
string _checkgeneration = "";
boolean _has_pcmcia = nil;
boolean _is_laptop = nil;
boolean _is_uml = nil;
boolean _has_smp = nil;
// Xen domain (dom0 or domU)
boolean _is_xen = nil;
// Xen dom0
boolean _is_xen0 = nil;
/* ************************************************************ */
/* system architecture                                          */
 * General architecture type
global string architecture () {
    if (_architecture == nil)
        _architecture = (string)SCR::Read(.probe.architecture);
    return _architecture;

outputs the following Ruby code
module Arch
  require 'ycp/SCR'
  _architecture = nil
  _board_compatible = nil
  _checkgeneration = ""
  _has_pcmcia = nil
  _is_laptop = nil
  _is_uml = nil
  _has_smp = nil
  _is_xen = nil
  _is_xen0 = nil

  def architecture(  )
    if ( _architecture == nil ) then
      _architecture = Ycp::Builtin::Read( ".probe.architecture" )
    return _architecture
Preserving the comments from the ycp code would be nice -- for next Hackweek.
Btw, it's fairly straightforward to change the translator to output e.g. Python or Java or C# or ...

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