52.9 Blinking Parentheses

This section describes the mechanism by which SXEmacs shows a matching open parenthesis when the user inserts a close parenthesis.

Variable: blink-paren-function

The value of this variable should be a function (of no arguments) to be called whenever a character with close parenthesis syntax is inserted. The value of blink-paren-function may be nil, in which case nothing is done.

Please note: This variable was named blink-paren-hook in older Emacs versions, but since it is not called with the standard convention for hooks, it was renamed to blink-paren-function in version 19.

Variable: blink-matching-paren

If this variable is nil, then blink-matching-open does nothing.

Variable: blink-matching-paren-distance

This variable specifies the maximum distance to scan for a matching parenthesis before giving up.

Variable: blink-matching-paren-delay

This variable specifies the number of seconds for the cursor to remain at the matching parenthesis. A fraction of a second often gives good results, but the default is 1, which works on all systems.

Command: blink-matching-open

This function is the default value of blink-paren-function. It assumes that point follows a character with close parenthesis syntax and moves the cursor momentarily to the matching opening character. If that character is not already on the screen, it displays the character’s context in the echo area.

To avoid long delays, this function does not search farther than blink-matching-paren-distance characters.

Here is an example of calling this function explicitly.

(defun interactive-blink-matching-open ()
  "Indicate momentarily the start of sexp before point."
  (interactive)

  (let ((blink-matching-paren-distance
         (buffer-size))
        (blink-matching-paren t))
    (blink-matching-open)))