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Re: do-nothing macro generates nil nevertheless
- To: firstname.lastname@example.org
- Subject: Re: do-nothing macro generates nil nevertheless
- From: email@example.com (Andrew Philpot)
- Date: Mon, 27 Feb 1995 21:15:46 GMT
- Organization: NASA/ARC Computational Sciences Division
- References: <firstname.lastname@example.org>, <email@example.com>, <Pine.A184.108.40.2060227130326.26069Jfirstname.lastname@example.org>
- Sender: email@example.com
In article <Pine.A220.127.116.110227130326.26069Jfirstname.lastname@example.org>,
William D. Gooch <email@example.com> wrote:
>On 27 Feb 1995, Dave Yost wrote:
>> My point is that some functionality is not provided:
>> namely, the ability of a macro to expand into _nothing_.
>Why not just use ,@(the-macro ...) ? Then if it returns nil, you get
>nothing. Of course, it must always return a list for this to work.
I thought of this approach as well. This has been my tactic in
similar situations in the past.
But I think in Dave Yost's case the invoking context is not
necessarily a backquote templating context, so ,@ might not be
possible. I believe the example had (PROGN ... (THE-MACRO)), not
`(PROGN ... ,(THE-MACRO)).
Recom Tech/NASA Ames