RE: How to travel into the future?

[Drew Adams]

> I'd like to use in my code the M-n facility in history to enable the
> user to have access to a reasonable default value, as described in
>   (info "(emacs) Minibuffer History").
> How should I do it?  Should I use read-string?  If so, do I have to put
> the default into the history variable and use the (HISTVAR . POSITION)
> argument to read-string?  If so, should I then manually delete the
> default (which might have been used or not by the user) from the history
> variable afterwards?
> 
> Any pointers?

Just provide a list of default values (strings) as argument
DEFAULT to `completing-read', `read-string', or similar.

`C-h f read-string':

 Fourth arg DEFAULT-VALUE is the default value or the list of default values.
 If non-nil, it is used for history commands, and as the value (or the first
 element of the list of default values) to return if the user enters the
 empty string.