blackboard.lsp

Autocad-2005-简体中文-解密版.zip

;;;                                                                    ;
;;;  BLACKBOARD.lsp                                                    ;
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;;;
;;;	 Blackboard Sample
;;;
;;;
;;; Sample file supplied by: 	Perceptual Engineering Inc.
;;; web:			www.perceptual-eng.com
;;; Author:			Ralph Gimenez, Perceptual Engineering
;;;
;;;
;;; Functions Used:
;;;
;;; This example will demonstrate the use of the blackboard 
;;; functions vl-bb-set, vl-bb-ref, as well as vl-propagate and defun-q. 
;;;
;;;
;;;
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Running the Example:

   1. Open a new drawing
   2. Load blackboard.lsp file into Visual LISP. 
   3. Once blackboard.lsp is loaded, you will receive the message 
      'Blackboard Example Initialized'
   4. Execute the c:documents function at the command prompt.
      You will see a list printed on the screen: (("Drawing1.dwg"))
   5. Create a new drawing
   6. Execute the c:documents function again at the command prompt.
      You will see a list printed on the screen:
      (("Drawing2.dwg")("Drawing1.dwg"))

   You may repeat this as many times as desired including switching back
   and forth between documents and evaluating c:documents.


Overview:

    This file uses the blackboard feature as a communication pipeline
    between documents to:

    	1. Provide new and updated AutoLISP function definitions 
    	   to all currently displayed documents as well as any 
    	   future documents created by the new or open command 
    	   without using vl-propagate. 

    	2. Provide default initialization values to any new document without 
    	   redefining the s::startup function.

    	3. Use the blackboard as a initialization font.

    	4. Provide communications without the use of reactors.
	
    	5. Provide the developer an additional API that 
    	   will retrieve, evaluate and place values during an 
    	   initialization of a document (whether by new or open)
    	   without overburdening s::startup.

    	6. Enable any application to place any information that 
    	   is required to be evaluated without modifying 
    	   s::startup or ACAD2000doc.lsp.

	7. Display a list of drawings that have been opened or created during
           this example.

    Initial communication is accomplished using a redefinition of the 
    s::startup function (if it exists). Otherwise a new s::startup 
    function is created.




Specifications:

	What is the Blackboard?

		The Help file states... 

		VLISP provides a blackboard namespace for communicating the values of
		variables between namespaces. The blackboard is a namespace that is not
		attached to any document or VLX application. You can set and reference
		variables in the blackboard from any document or VLX. Use the vl-bb-set
		function to set a variable, and use vl-bb-ref to retrieve a variable's
		value. 

		Referencing Variables in Document Namespaces

		Variables defined in a separate-namespace VLX are not known to the
		document namespace associated with the VLX. However, a
		separate-namespace VLX can access variables defined in a document
		namespace using the vl-doc-ref and vl-doc-set functions. The vl-doc-ref
		function retrieves the value of a variable from a document namespace.
		The function requires a single argument, a symbol identifying the
		variable to be retrieved. For example, the following function call
		retrieves the value of a variable named aruhu:

		(setq var1 (vl-doc-ref 'aruhu))

		If executed within a document namespace, vl-doc-set is equivalent to the
		set function. The vl-doc-set function sets the value of a variable in a
		document namespace. The function requires two arguments: a symbol
		identifying the variable to be set, and the value to set the variable
		to. For example, the following function call sets the value of a variable
		named ulus:

		(vl-doc-set 'ulus "Go boldly to no one")

		If executed within a document namespace, vl-doc-ref is equivalent to the
		eval function. To set the value of a variable in all open document
		namespaces, use the vl-propagate function. For example, the following
		function call sets a variable named fooyall in all open document
		namespaces:

		(vl-propagate 'fooyall)

		This command not only copies fooyall into all currently open document
		namespaces, but also causes fooyall to be automatically copied to the
		namespace of any new drawings opened during the current AutoCAD session.

		Please Note:  
		       
		       Any function which has been "propagated" is available 
			   after AutoCAD has completed the initialization of a new 
			   or opened document. This limitation is evident when a
			   propagated function is used within the s::startup function.

			Example:

			   1. Define this code fragment in the Visual LISP console:

				(defun-q print-list (lst)
					 (foreach item lst
					    (prin1 item)
					   (terpri)
					   )
					 (princ)
					 )

				(vl-propagate 'print-list) ;; propagate the function to all documents

				(defun s::startup ()
				    (print-list '( 1 2 3 4 5 6 7 ))
				)
				(vl-propagate 's::startup) ;; propagate the function

			  2. Create a new drawing and watch the error produced by s::startup.

			     When s::startup is executed you will receive the error:

				; *** ERROR: no function definition: PRINT-LIST


	Sample Code Documentation:

	Mechanism and Flow:

	* Functions defined in this file 
	  and the mechanics behind the functions.
		
		The first function defined in this file is
        ac:register-function-to-blackboard.  This function is
        responsible for updating the value of the global list  
        *shared-functions* and placing its updated value to 
        the blackboard.

        The function ac:evaluate-Blackboard-items is called only 	
		within the body of the modified s::startup function. When 
		AutoCAD automatically calls the s::startup function whenever 
		a new drawing is created, s::startup calls 
		ac:evaluate-Blackboard-items, retrieving the current value 
		of the global list *shared-functions*.  Every item in this
		list is then evaluated within the context of the new 
		drawing.

 
        ac:register-mdi-drawing-names is a function that is placed 
		in the *shared-functions* variable. Moreover, this function 
		is called at each <drawing new> or <drawing open> command 
		because s::startup initializes the document with the