[asdf-devel] Question about use of :unspecific

[james anderson]

On 2010-03-16, at 04:32 , Faré wrote:

>>> [ ... ]
>
>> It seems like either these pathnames are never subjected to
>> MERGE-PATHNAMES, in which case we can just always return NIL, or they
>> /are/ sometimes subjected to MERGE-PATHNAMES, in which case sometimes
>> the use of NIL instead of :unspecific will cause oddities (unless the
>> default type is always empty).
>>
> Using :UNSPECIFIC seemed like it might produce more robust code.
> But now that I realize the unportability, I don't care as much.
>
> SBCL, CCL and LispWorks all pass janderson's tests just as well with
> either NIL or :UNSPECIFIC. Haven't counted failures in other  
> implementations.


past experience with pathname portability led to the proposed patch  
to the pathname merge operator to construct a contingent argument  
list to make-pathname. where no component is to be specified, none is  
passed to make-pathname. if the context is such that one does not  
need to block a default component, that tactic should be sufficient.

my recollection is that it worked for all tested implementations.