Grooves: why are "data" designed as properties and not nodes ?
Anders W. Tell
anderst at toolsmiths.se
Sat Sep 25 17:01:18 BST 1999
"Steven R. Newcomb" wrote:
> [Anders W. Tell:]
> * The SGML Property Set, which is an instance of a property set as
> defined by the grove paradigm, is somewhat comparable to the DOM.
> The DOM is not directly comparable to the grove paradigm. Maybe
> your current "DOM-compliant" model is comparable to the grove
> paradigm, though (depending on what it is).
Yes almost, however the nodes are values, simple or constructed.
> > Could somone explain the design rationale why properties and not node
> > carries data ?
> Properties do not "contain" data. Properties are like variables: they
> can "have" values.
> A node *consists* of a set of named properties and their values, if
> any. A node (an instance of a class of nodes) can have many
> properties. Some properties are "data" properties; this means that,
> unlike "nodal" properties, their values must be data, and cannot be
> nodes. If nodes were the same thing as data, or if nodes could be
> treated as data, then they would have only one property, whose value
> would be the data. That would not be as useful as having nodes
> consisting of any number of named properties, any number of which can
> be data properties.
So if I understand it correctly, when Propertys have values then Nodes are *multi-valued*
which differes from the case when nodes are values themselfs.
An example how this design might be used:
Serialization of a programming language "Object"
Freeform PropertySet: "Objects"
"Members": NodeList , restricted to Nodes of class "ProgMember"
"c++-type" : string
"c++-value" : any property type, restricted to the "c++-type" types of values
"visualbasic-type" : string
"visualbasic-value" : any property type, restricted to the "visualbasic+-type" types of
And if I want to treat this Grove as C++ Object then I apply a Grove-plan which
"filters" out all "visualbasic-x" properties or keeps the "c++-X" properties.
> > Does this design imply that tree-algorithms are easier to implement ?
> The design of the grove paradigm is explicitly intended not to imply
> anything at all about implementation.
Ok, but what about algorithms that uses the Grove?
(how Information is organized does affect algorithms
even if the "organization" is generic.)
/ Financial Toolsmiths AB /
/ Anders W. Tell /
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