xnomo3.py: Internal maintenance specification

Since users do not need to call this constructor directly, it functions only during the translation of XML nodes. Accordingly, the constructor takes two arguments: a pointer back to the containing Hier instance, and the node describing the rank.

# - - - - -   c l a s s   R a n k   - - - - -

class Rank:
    """Represents one taxonomic rank.

      Exports:
        Rank ( hier, rankNode ):
          [ (hier is the containing Hier instance) and
            (rankNode is a RANK_N node) ->
              return a new Rank instance in hier representing
              rankNode ]
        .code:      [ self's rank code ]
        .depth:     [ self's depth, 0 for the root ]
        .keyLen:    [ length of self's portion of the taxonomic key ]
        .name:      [ English name of the rank ]
        .isOptional:
          [ if this rank can be omitted -> 1
            else -> 0 ]
    """

Here is the trivial constructor.

# - - -   R a n k . _ _ i n i t _ _   - - -

    def __init__ ( self, hier, rankNode ):
        """Constructor for a Rank instance.
        """

        #-- 1 --
        self.hier = hier

        #-- 2 --
        # [ self.code        :=  the CODE_A attribute of rankNode
        #   self.depth       :=  the DEPTH_A attribute of rankNode as int
        #   self.keyLen      :=  the DIGITS_A attribute of rankNode
        #   self.name        :=  the text content of rankNode
        #   self.isOptional  :=  true iff rankNode has an
        #                        OPTIONAL_A attribute ]
        self.code = rankNode.attrib[rnc.CODE_A]
        self.depth = int ( rankNode.attrib[rnc.DEPTH_A] )
        self.keyLen = int ( rankNode.attrib[rnc.DIGITS_A] )
        self.name = rankNode.text.strip()
        self.isOptional = int ( rankNode.attrib.get(
                                  rnc.OPTIONAL_A, 0) )