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From: mark@cambridge.apple.com (Mark Preece)
Newsgroups: comp.lang.lisp
Subject: Re: ~V directive in format statments
Message-ID: <780@ministry.cambridge.apple.com>
Date: 11 Feb 91 22:43:04 GMT
References: <TESKRIDG.91Feb11120557@illyria.nmsu.edu>
Reply-To: mark@cambridge.apple.com (Mark Preece)
Distribution: comp.lang.lisp
Organization: . .
Lines: 26

In article <TESKRIDG.91Feb11120557@illyria.nmsu.edu> teskridg@nmsu.edu (Tom Eskridge) writes:
>
>I came across a piece of code which uses the ~V directive to pass an
>arguement to the ~T (tab) directive in a format statement.  So
>   (format nil "~VThello" 3) => "   hello"

[stuff deleted]
>
>the ~V is not documented in either CLtL I or II.  Does anyone have any info on
>this? 
>

Actually, it is documented in CLTL/II (but - like a certain amount of the
format stuff - really hard to find). On page 582:

	In place of a prefix parameter to a directive, you can put the 
	letter V (or v), which takes an argument from _arguments_ for
	use as a parameter to the directive. Normally this should be an
	integer or character object, as appropriate. This feature allows
	variable-width fields and the like. If the argument used by a V
	parameter is nil, the effect is as if the parameter had been omitted.

It's not the ~V command (the "~" doesn't belong to the V, but to the command
it modifies).

- Mark.