Extra arg in interactive?

Extra arg in interactive?

[zslevin]

I find it handy in string input to use the region string if it is active, or 
read from user if it is not.

So I usually have:
  (interactive "Mphrase: \n")

replaced with:

  (interactive (list (or (and mark-active
			transient-mark-mode
			(buffer-substring-no-properties
			 (region-beginning)
			 (region-end)))
		   (read-string "phrase: "))))

If an extra arg in interactive does this as well, that saves lots of work.

Thank you
-Levin

Re: Extra arg in interactive?

[Richard Stallman]

    I find it handy in string input to use the region string if it is active, or 
    read from user if it is not.

For some commands, this could be natural.  But there are commands
for which it doesn't make sense, such as write-region.