Re: [Sbcl-devel] [PATCH] more reader cleanups

[Tobias C. R. <tc...@fr...>]

Christophe Rhodes <cs...@ca...> writes:

> "Tobias C. Rittweiler" <tc...@fr...> writes:
>
>> * make-d-macro-char.diff
>>
>>    Currently, invoking MAKE-DISPATCH-MACRO-CHARACTER on a character
>>    that's already been made a dispatch macro character results in an
>>    error.
>>
>>    All other implementations I tested, do not signal an error, but just
>>    override a possibly existing dispatch table.
>>
>>    I think that's sensible, as the the CLHS entry for MAKE-D-M-CHAR says
>>    Exceptional Situations are None.
>
> That is not a good enough reason for not signalling an error; the CLHS
> makes no attempt to be exhaustive about exceptional situations.  I'm
> not at all convinced that overriding a possibly-existing dispatch
> table is a sensible thing to do at all; allowing the user to delete
> data doesn't sound like a win to me.

It's the second paragraph of MAKE-D-M-CHAR + Exceptional Situations
being None:

  ``Initially, every character in the dispatch table associated with the
    char has an associated function that signals an error of type
    reader-error.''

Reading both in combination makes overriding a plausible choice in my
view.

  -T.