37.21 Blinking Parentheses

This section describes the mechanism by which Emacs 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.

User Option: blink-matching-paren

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

User Option: blink-matching-paren-distance

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

User Option: blink-matching-delay

This variable specifies the number of seconds to keep indicating 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 applies the appropriate effect 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 parenthesized sexp before point."
  (interactive)

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