12 The LISPWORKS Package

with-file-stats

Macro

Summary

Returns information on a file.

Package

lispworks

Signature

with-file-stats (&rest stats) pathname if-form if-not-form => form-result

Arguments

stats: Any of: author, length, write-date.
pathname: A pathname.
if-form: A form that gets executed if the pathname can be accessed.
if-not-form: A form that gets executed if the pathname cannot be accessed.

Values

form-result: The result of executing whichever of if-form and if-not-form is executed.

Description

Thewith-file-stats macro is a more efficient way of interrogating a file for author, length, and write-date if more than one needs to be known.

Example

Without this function, a simple file interrogation function might look like this:

(defun print-file-info (pathname) 
  (if (file-readable-p pathname) 
      (format t "~%Author: ~A~%Size: ~A~%Write-Date: ~A~%" 
      (file-author pathname) 
      (file-length pathname) 
      (file-write-date pathname)) 
    (format t "Cannot read ~A" pathname)))

: The function can be written more efficiently usingwith-file-stats:

(defun print-file-info (pathname) 
  (with-file-stats (author length write-date) pathname 
   (format t "~%Author: ~A~%Size: ~A~%Write-Date: ~A~%" 
author 
length 
write-date 
(format t "Cannot read ~A" pathname))))