The Visual LISP 编辑器介绍

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The Visual LISP Editor - Part 1

This tutorial is a crash course in using the Visual LISP Editor, and is not intended to be detailed or fully comprehensive. The aim is to show you the main functions of the Editor with the intention of getting you up and running as quickly as possible.

Right, enough waffle, let's get started. Fire up AutoCAD and open a new drawing. Now choose Tools

The Visual LISP 编辑器介绍

AutoLISP

The Visual LISP 编辑器介绍

Visual LISP Editor from the pull-down menu. If you don't see the pull-down menu, enter menubar at the command prompt and set the value to 1.

The Visual Lisp Editor will open and should look like this :

The Visual LISP 编辑器介绍

Let's start off by having a look at the Visual LISP Console window :

The Visual LISP 编辑器介绍

The VLISP Console window is similar in some respects to the AutoCAD Command window, but has a few extra features. You enter text into the Console window following the Console prompt which looks like this :

_$

Type this in the Console prompt and then press "Enter" :

_$ (setq a "Test")

Now type this and again press "Enter" :

_$ a

Your Console window should look like this :

The Visual LISP 编辑器介绍

To view the value of a variable at the AutoCAD Command prompt, you must precede the variable name with an exclamation mark. ( ! ) In VLISP, you simply type the variable name.

Unlike the AutoCAD Command window, where pressing SPACEBAR causes expression evaluation, text input at the VLISP Console prompt is not processed until you press ENTER. This permits you to do the following in the Console window:

• Continue an AutoLISP expression on a new line. To continue entering an expression on a new line, press CTRL +ENTER at the point you want to continue.
• Input more than one expression before pressing ENTER. VLISP evaluates each expression before returning a value to the Console window.
• If you select text in the Console window (for example, the result of a previous command or a previously entered expression), then press ENTER, VLISP copies the selected text at the Console prompt.
  

The VLISP Console window and the AutoCAD Command window differ in the way they process the SPACEBAR and TAB keys. In the VLISP Console window, a space plays no special role and serves only as a separator. In the AutoCAD Command window, pressing the SPACEBAR outside an expression causes AutoCAD to process the text immediately, as if you had pressed ENTER.

Using the Console Window History

You can retrieve text you previously entered in the Console window by pressing TAB while at the Console prompt. Each time you press TAB, the previously entered text replaces the text at the Console prompt. You can repeatedly press TAB until you cycle through all the text entered at the Console prompt during your VLISP session. After you’ve scrolled to the first entered line, VLISP starts again by retrieving the last command entered in the Console window, and the cycle repeats. Press SHIFT + TAB to scroll the input history in the opposite direction. For example, assume you entered the following commands at the Console prompt:

(setq origin (getpoint "\nOrigin of inyn sign: "))(setq radius (getdist "\nRadius of inyn sign: " origin))(setq half-r (/ radius 2))(setq origin-x (car origin))(command "_.CIRCLE" origin radius)

To retrieve commands entered in the Console window :

• Press TAB once. VLISP retrieves the last command entered and places it at the Console prompt :
  _$ (command "_.CIRCLE" origin radius)
• Press TAB again. The following command displays at the Console prompt :
  _$ (setq origin-x (car origin))
• Press TAB again. VLISP displays the following command :
  _$ (setq half-r (/ radius 2))
• Now press SHIFT+ TAB . VLISP reverses direction and retrieves the command you entered after the previous command :
  _$ (setq origin-x (car origin))
• Press SHIFT+ TAB again. VLISP displays the following command :
  _$ (command "_.CIRCLE" origin radius)
  This was the last command you entered at the Console prompt.
• Press SHIFT+ TAB again. Because the previous command retrieved was the last command you entered during this VLISP session, VLISP starts again by command you entered in the Console window :
  _$ (setq origin (getpoint "\nOrigin of inyn sign: "))
  

Note : If you enter the same expression more than once, it appears only once as you cycle through the Console window input history. You can perform an associative search in the input history to retrieve a specific command that you previously entered. To perform an associative search of the Console input history :

• Enter the text you want to locate. For example, enter (command at the Console prompt :
  _$ (command
• Press TAB. VLISP searches for the last text you entered that began with (command :
  _$ (command "_.CIRCLE" origin radius)
  If VLISP does not find a match, it does nothing (except possibly emit a beep). Press SHIFT+ TAB to reverse the direction of the associative search and find progressively less-recent inputs.
  
  

Interrupting Commands and Clearing the Console Input Area

To interrupt a command entered in the Console window, press SHIFT + ESC. For example, if you enter an invalid function call like the following:

_$ ((setq origin-x (car origin)((_>

Pressing SHIFT + ESC interrupts the command, and VLISP displays an "input discarded" message like the following :

((_> ; <input discarded>_$

If you type text at the Console prompt, but do not press <Enter>, then pressing ESC clears the text you typed. If you press SHIFT + ESC, VLISP leaves the text you entered in the Console window but displays a new prompt without evaluating the text.

If you type part of a command at the Console prompt, but activate the AutoCAD window before pressing <Enter>, VLISP displays a new prompt when you next activate the VLISP window. The text you typed is visible in the Console window history, so you can copy and paste it, but you cannot retrieve the text by pressing TAB , because it was not added to the Console history buffer.

When you're ready, let's continue Part 2.

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The Visual LISP Editor - Part 2

Right, enough messing about. Let's load some coding. Choose File New File and then copy and paste this coding into the text editor :

(defun C:SLOT ()

  (setvar "CMDECHO" 0)

  (setvar "BLIPMODE" 0)

  (setq oldsnap (getvar "OSMODE"))

  (setq diam (getdist "\nSlot Diameter : ")

        lngth (getdist "\nSlot Length : ")

  )

  (while

    (setq pt1 (getpoint "\nInsertion point:"))

    (setvar "OSMODE" 0)

    (setq pt2 (polar pt1 0.0 (/ (- lngth diam) 2.0))

          pt3 (polar pt2 (/ pi 2.0) (/ diam 4.0))

          pt4 (polar pt3 pi (- lngth diam))

          pt5 (polar pt4 (* pi 1.5) (/ diam 2.0))

          pt6 (polar pt5 0.0 (- lngth diam))

    )

    (command "PLINE" pt3 "W" (/ diam 2.0) "" pt4 "ARC" pt5 "LINE" pt6 "ARC"

             "CLOSE"

    )

    (setvar "OSMODE" oldsnap)

  )                                       ; while

  (princ)

)

</font></font></font></div><div align=\"left\"><font face=\"Arial, Helvetica, sans-serif\"><font color=\"#000000\"><font style=\"font-size:12.8px\"><div align=\"left\">(defun C:SLOT ()</div><br /> <div align=\"left\">  (setvar "CMDECHO" 0)</div><div align=\"left\">  (setvar "BLIPMODE" 0)</div><div align=\"left\">  (setq oldsnap (getvar "OSMODE"))</div><br /> <div align=\"left\">  (setq diam (getdist "\nSlot Diameter : ")</div><div align=\"left\">        lngth (getdist "\nSlot Length : ")</div><div align=\"left\">  )</div><br /> <div align=\"left\">  (while</div><div align=\"left\">    (setq pt1 (getpoint "\nInsertion point:"))</div><div align=\"left\">    (setvar "OSMODE" 0)</div><div align=\"left\">    (setq pt2 (polar pt1 0.0 (/ (- lngth diam) 2.0))</div><div align=\"left\">          pt3 (polar pt2 (/ pi 2.0) (/ diam 4.0))</div><div align=\"left\">          pt4 (polar pt3 pi (- lngth diam))</div><div align=\"left\">          pt5 (polar pt4 (* pi 1.5) (/ diam 2.0))</div><div align=\"left\">          pt6 (polar pt5 0.0 (- lngth diam))</div><div align=\"left\">    )</div><br /> <div align=\"left\">    (command "PLINE" pt3 "W" (/ diam 2.0) "" pt4 "ARC" pt5 "LINE" pt6 "ARC"</div><div align=\"left\">             "CLOSE"</div><div align=\"left\">    )</div><div align=\"left\">    (setvar "OSMODE" oldsnap)</div><div align=\"left\">  )                                       ; while</div><div align=\"left\">  (princ)</div><div align=\"left\">)</div><div align=\"left\">

The coding should look like this in the text editor :

Before we go any further, let's have a wee chat about the colors. As soon as you enter text in the VLISP Console or text editor windows, VLISP attempts to determine if the entered word is a built-in AutoLISP function, a number, a string, or some other language element. VLISP assigns every type of element its own color. This helps you detect missing quotes or misspelled function names. The default color scheme is shown in the following table.

AutoLISP Language Element	Color
Built-in functions and protected symbols	Blue
Strings	Magenta
Integers	Green
Real numbers	Teal
Comments	Burgundy, on gray background
Parentheses	Red
Unrecognized items (for example, user variables)	Black

You can change the default colors. But, do yourself a favour. Don't!

Selecting Text

The simplest method to select text is to double-click your left mouse button. The amount of text selected depends on the location of your cursor.

• If the cursor immediately precedes an open parenthesis, VLISP selects all the following text up to the matching close parenthesis.
• If the cursor immediately follows a close parenthesis, VLISP selects all preceding text up to the matching open parenthesis.
• If the cursor immediately precedes or follows a word, or is within a word, VLISP selects that word.
  

Hint : Would you like help on any AutoLisp function? Double-click on the function name to select it, and then select the "Help" toolbar button. Help for the specific function will be displayed.

To load the "Slot" lisp routine, select the "Load active edit window" toolbar button :

This loads your coding into memory. To run the routine, type this at the Console prompt :

_$ (c:slot)

The program should now run, switching over to the AutoCAD screen when required. You can also just run a selection of code if you desire. Select the lines of code you would like to run and choose the "Load selection" toolbar button, and then press "Enter."

Only the lines of code you selected will be run, Great for debugging.

Talking about debugging, Place the cursor in front of the (defun C:SLOT () statement and press "F9". This places a "Breakpoint" into your program. Now run the program again. Execution should stop at the Breakpoint mark. Now press "F8". By continuously pressing "F8" you can "single step" through your whole program :

Let's go one step further. Select the "diam" variable and then select the "Add Watch" toolbar button :

The "Watch" dialog box will appear :

Note how the variable "diam" is listed along with it's present value. Repeat this process for all the other variables until the Watch" dialog looks like this :

Now run the program again, still "single" stepping through. Notice how the values of the variables change as the program proceeds.

OK let's liven things up a bit. Select "Ctrl-Shift-F9" to clear all breakpoints. Now select the "Debug" pull down menu and then "Animate". Now run the program again.

Hey, it's running automatically! Take note of the variables changing in the "Watch" window as the program does it's thing.

Well that's about it in regards to the Visual LISP Editor. The editor has a lot more functions than I've shown you here, but these I feel, are some of the more important ones to get you started.