link.md
In rswipl: Embed 'SWI'-'Prolog'

class link {#class-link}

A link object describes the reusable part of a connection object. A connection is a line object between two graphicals, attached to handle objects defined on those graphicals or on their classes.

The reusable link contains the handle<-kind of the handles required at the start- and endpoint of the line and a prototype for the line (with the appropriate texture, pen, arrows, etc).

See also example Linking Graphicals, class connection and class handle.

@see topic Connections @see class connection @see class handle

link<->connection_class: [class] Class used by <-connection. This must be a subclass of class connection. If the value is @default, this slot will be set to class(connection) on the first call to <-connection.
link<->from: name The connection instantiated from this link may connect to any handle that has handle <-kind equal to the value of this variable at the indicated end.
link<->to: name Inherits description from: link-from

link->initialise: handle_kind1=[name], handle_kind2=[name], line=[line], connection_class=[class] Define a link which may connect to a handle with handle <-kind is handle_kind1 at the connection<-from end and handle <-kind is handle_kind2 at the connection<-to end.

The default handle_kind1 is link. The default handle_kind2 is handle_kind1. The default line is an instance of class line create with no arguments.

The connection_class argument determines the class used by <-connection to instantiate the link. The default is class connection.

link<-connection: from=graphical, to=graphical, from_handle=[name], to_handle=[name] -> connection Creates an instance of the link. An instance of a link object is a connection object. This method is normally called from graphical ->connect.

The default implementation of this method creates an instance of class <-connection_class using the arguments passed to this method. See connection ->initialise.