RE: delete-file default to buffer-file-name if non-nil

[Drew Adams]

> > 1. Insert the default value in the minibuffer. This assumes that the
> > greatest danger is hitting RET without seeing what the file to be
> > deleted is.
> 
> The argument INITIAL-CONTENTS is obsolete and should not be used.
> It's possible to insert the default value to the minibuffer 
> with `M-n'.

So it is.  But I happen to disagree that it should be obsolete. ;-)

A better approach is to let the user decide the behavior.
I have this option (FWIW):

,----
| icicle-default-value is a variable defined in `icicles-opt.el'.
| Its value is t
| 
| Documentation:
| How to treat the default value when reading minibuffer input.
| 
| When the default value argument to functions such as
| `completing-read', `read-file-name', `read-from-minibuffer', and
| `read-string' is non-nil and the initial-input argument is nil or
| "", the default value can be added to the prompt as a hint or
| inserted into the minibuffer as the initial input.
| 
| Adding it to the prompt is the default behavior and corresponds to the
| behavior of vanilla Emacs.
| 
| Inserting the default value in the minibuffer as the initial input has
| the advantage of not requiring you to use `M-n' to retrieve it.  It
| has the disadvantage of making you use `M-p' (or do something else) to
| get rid of the default value in the minibuffer if you do not want to
| use or edit it.  If you often want to use or edit the default value,
| then set `icicle-default-value' to non-nil and non-t.  If you rarely
| do so, then set it to nil or t.
| 
| If inserted in the minibuffer, the value of this option also
| determines whether or not the inserted text is preselected and where
| the cursor is left: at the beginning or end of the text.
| 
| These are the possible option values:
| 
|   nil               - Do not insert default value or add it to prompt.
|   t                 - Add default value to prompt.  Do not insert it.
|   `insert-start'    - Insert default value and leave cursor at start.
|   `insert-end'      - Insert default value and leave cursor at end.
|   `preselect-start' - Insert and preselect default value;
|                       leave cursor at beginning.
|   `preselect-end'   - Insert and preselect default value;
|                       leave cursor at end.
| 
| My own preference is `insert-end'.
| 
| Preselection can be useful in Delete Selection mode or PC Selection
| mode.  It makes it easy to replace the value by typing characters, or
| delete it by hitting `C-d' or `DEL' (backspace).  However, all of the
| initial input is lost if you type or hit `C-d' or `DEL'.  That is
| inconvenient if you want to keep most of it and edit it only slightly.
| 
| You can customize this variable.
`----