Pausing for User Input

If an AutoCAD command is in progress and the predefined symbol PAUSE is encountered as an argument to command, the command is suspended to allow direct user input (usually point selection or dragging). This is similar to the backslash pause mechanism provided for menus.

The PAUSE symbol is defined as a string consisting of a single backslash. When you use a backslash (\) in a string, you must precede it by another backslash (\\).

Menu input is not suspended by an AutoLISP pause. If a menu item is active when the command function pauses for input, that input request can be satisfied by the menu. If you want the menu item to be suspended as well, you must provide a backslash in the menu item. When valid input is found, both the command function and the menu item resume.

NoteYou can use a backslash instead of the PAUSE symbol. However, it is recommended that you always use the PAUSE symbol rather than an explicit backslash. Also, if the command function is invoked from a menu item, the backslash suspends the reading of the menu item, which results in partial evaluation of the AutoLISP expression.

If you issue a transparent command while a command function is suspended, the command function remains suspended. Therefore, users can 'ZOOM and 'PAN while at a command pause. The pause remains in effect until AutoCAD gets valid input, and no transparent command is in progress. For example, the following code begins the CIRCLE command, sets the center point at (5,5), and then pauses to let the user drag the circle's radius. When the user specifies the desired point (or types in the desired radius), the function resumes, drawing a line from (5,5) to (7,5), as follows:

(command "circle" "5,5" pause "line" "5,5" "7,5" "")

If PAUSE is encountered when a command is expecting input of a text string or an attribute value, AutoCAD pauses for input only if the TEXTEVAL system variable is nonzero. Otherwise, AutoCAD does not pause for user input but uses the value of the PAUSE symbol (a single backslash) text.

When the command function pauses for user input, the function is considered active, so the user cannot enter another AutoLISP expression to be evaluated.

The following is an example of using the PAUSE symbol (the layer NEW_LAY and the block MY_BLOCK must exist in the drawing prior to testing this code):

(setq blk "MY_BLOCK")

(setq old_lay (getvar "clayer"))

(command "layer" "set" "NEW_LAY" "")

(command "insert" blk pause "" "" pause)

(command "layer" "set" old_lay "")

The preceding code fragment sets the current layer to NEW_LAY, pauses for user selection of an insertion point for the block MY_BLOCK (which is inserted with X and Y scale factors of 1), and pauses again for user selection of a rotation angle. The current layer is then reset to the original layer.

If the command function specifies a PAUSE to the SELECT command and a PICKFIRST set is active, the SELECT command obtains the PICKFIRST set without pausing for the user.

WarningThe Radius and Diameter subcommands of the Dim prompt issue additional prompts in some situations. This can cause a failure of AutoLISP programs written prior to Release 11 that use these commands.