Re: Macro Expansion Inconsistency

[Joost Kremers]

Alexander Shukaev wrote:
> (defmacro test
>     (name)
>   `(let* ((name             ',name)
>           (symbol           (intern (concat "some" "-" (symbol-name name)))))
>      ,symbol))
>
> Running
>
> (test xxx)
>
> reports error: (void-variable symbol).
>
> What?
>
> Refactoring to
>
> (defmacro test
>     (name)
>   `(let* ((name             ',name))
>      ,(intern (concat "some" "-" (symbol-name name)))))
>
> and running
>
> (test xxx)
>
> works as expected.
>
> Could anybody clarify what's going on? Thanks.

Just consider when exactly the different parts of your macro are
evaluated. When is something that is quoted in the definition evaluated?
And when is something that is comma-escaped evaluated? Then look
carefully at what is quoted and what is comma-escaped. You'll see that
in the first version, something doesn't match.


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)