Deprecated! Needs review.

How to write new types for KnowWE#

If you dont know what a KnowWE type is, first have a look: KnowWEType

The class AbstractKnowWEObjectType#

This class implements KnowWEObjectType and also contains some helpfull features implemented. Some more default-implementations for optional methods are given in its subclass DefaultAbstractKnowWEObjectType, which is recommened for use (see below).

Extend the class DefaultAbstractKnowWEObjectType#

This class should be extended when introducing new types to KnowWE (e.g., in a module). To enable real use of the type in the KDOMs of the pages at least a parsing-component, a SectionFinder, needs to be specified. This SectionFinder gets parts of the text and marks/allocates sections within this text that should be created as a section-node of the type. Further, if the types needs to have some specific look in the page view a KnowWEDomRenderer can be specified.

Here the example for a TableLineType is given, using the init() method to specify SectionFinder, Renderer and children-types:

public class TableLine extends DefaultAbstractKnowWEObjectType {
	
	@Override
	protected void init() 
	{
		childrenTypes.add(new TableCell());
		sectionFinder = new TableLineSectionFinder( this );
		setCustomRenderer(new TableLineRenderer());
	}
}

Explanation:
On system initialization time the init method is called. childrenTypes, sectionFinder and setCustomRendererare inherited from (Default)AbstractKnowWEObjectType. TableCell is a KnowWEType again and adding this to the children list denotes, that every TableLine will be split into TableCells. The sectionFinder sets the parsing-component for the local type. Thus, the TableLineSectionFinder should recognize Table-lines. The text-sections recognized by the SectionFinder are the text-content of the nodes of the corresponding type. Further, a custom renderer is set, that specifies how a table-line should be renderered. Being copied from the KnowWE source, this Type is full functional (given correct implementations of TableCell, TableLineSectionFinder and TableLineRenderer).

About SectionFinders#

Writing the SectionFinders for the new types typically is most of the overall work. If it is not absolutely necessary to have a custom syntax it is much less work to either use TagHandlers HowToWriteATagHandler or to use XML-syntax, for which parser components are already contained in KnowWE HowToWriteXMLTypes. <tags>HowTo</tags>

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This page (revision-1) was last changed on 17-Dec-2012 15:27 by Daniel Z├╝gner