Re: (copy-marker nil)

["Andreas Röhler" <andreas.roehler@easy-emacs.de>]

On 07.05.2018 16:26, Drew Adams wrote:
>>> For most functions, passing nil for an &optional parameter is the same
>>> as omitting it.
>>> If MARKER is not specified, the new marker does not point anywhere.
>>
>> It's about the return value.
>> A marker pointing nowhere, might it be considered valid?
> 
> What do you mean by "valid"?  Yes, it's a marker.  No, it
> doesn't have a buffer or position.  The same is true of
> other Emacs-Lisp objects, such as overlays: they can exist
> without having non-nil values for certain of their properties.
> 
>> Expected such returning nil.
> 
> Why?  The doc string is pretty clear that it returns a
> marker.  And it is clear what happens if arg MARKER is
> nil: "the new marker does not point anywhere".
> 


Is there a use-case for a marker pointing nowhere?
 From my point of view refusing to create such a marker makes sense.