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RE: alists with precomputed variables


From: Drew Adams
Subject: RE: alists with precomputed variables
Date: Tue, 20 Jan 2009 23:54:14 -0800

> > (setq my-alist `((p1 . 10) (p2 ,@my-var)))
> 
> I guess that might work, but ,@ is supposed to be followed by an 
> expression that returns a list, so that it can be spliced into the 
> containing list.  It would be better to write:
> 
> (setq my-alist `((p1 . 10) (p2 . ,my-var)))

I don't know about "supposed to be" (not only lists are spliced into list
structure), but yes, `.' followed by `,' might be clearer for an atom. But if I
didn't know the value of `my-var', I would probably use `,@', personally.

Anyway, the important thing is to read up on lists in the doc.
There are several ways to get something like what was requested.

The variants I gave are not all equivalent, in any case. In particular, '(p1 .
10) is typically not the same as (cons 'p1 10), in many contexts.





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