4.1.1 Nodetype structures

The apptree package support several 'nodetypes', described by a structure that must be only manipulated via the apptree API. Each nodetype is displayed in a different way, and with different associated bindings. In that way, the apptree package permits to create several types of nodes, as projects, datamodels, documentation nodes, etc. I hope this to be a sufficiently scalable design in order to support future Ferret development (support more types of nodes).

Each nodetype has some associated attributes:

• A string for identify this type of node. It must begin with an upper case letter, and contain only letters.
• An image to show with nodes of that type.
• A text type indicator, that appears as a prefix on the node text surrounded by parenthesis.

  If the prefix string is empty, then no parentheis are drawn.

• The type of the parent.
• The preferred order into the parent child list.
• It can be a positive number for a concrete order number, or one of the keywords {first} and {last}.
• A primary action callback, that is invoked when the user click on the node (both text and image) with the left button of the mouse. The concrete node name ({nodetype-instancename}) is appended to the callback script.

  Note that code for actually selecting the node on the Tree widget is also appending.

• A secondary action callback, that is invoked when the user click on the node (both text and image) with the middle button of the mouse.

  Note that code for actually selecting the node on the Tree widget is also appending.

• A context menu structure, that defines a popup menu that is activated by clicking on the node (both text and image) with the right button of the mouse.

  Example:

       
         { {"New project" project::new}
           {"Open a new project" project::open}
           {Separator}
           {"Close project" project::close} }
  

  Note that all the nodetype related information is keeping by the apptree package itself. So every client of the apptree package should use only its exported API.