The comps.xml file is used to populate Categories/Groups in package management  frontends. Examples are yum and 'pirut' (GUI).
Below is a class that implements TranslationDb for use with Dogtail. It has dependancy on yum.
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from yum.comps import Comps

class CompsXMLTranslationDb(TranslationDb):
    def __init__(self, compsFile, language):
        _comps = Comps()
        _comps.add(compsFile)
        self._strings = {}
        # load all strings into a dictionary structure
        for g in _comps._groups.values():
            if g.translated_name.has_key(language):
                self._strings[g.name] = g.translated_name[language]
                
        for c in _comps._categories.values():
            if c.translated_name.has_key(language):
                self._strings[c.name] = c.translated_name[language]

        del _comps

    def getTranslationsOf(self, srcName):
        result = []
        if self._strings.has_key(srcName):
            result.append(self._strings[srcName])
        return result
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