From: Tom Eskridge
Subject: ~V directive in format statments
Date: Mon, 11 Feb 1991 19:05:57 +0000
Message-ID: <TESKRIDG.91Feb11120557@illyria.nmsu.edu>

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"

it also seems to work with other ~ directives too, such as ~A. So,
  (format nil "~VA" 10 'hello) => "hello     "

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


tom eskridge
computing research laboratory, new mexico state university
········@nmsu.edu (505) 646-6247
--
tom eskridge
computing research laboratory, new mexico state university
········@nmsu.edu (505) 646-6247

• Re: ~V directive in format statments Jeffrey Mincy
• Re: ~V directive in format statments Mark Preece

From: Jeffrey Mincy
Subject: Re: ~V directive in format statments
Date: Mon, 11 Feb 1991 19:53:10 +0000
Message-ID: <1991Feb11.195310.11894@Think.COM>

In article <······················@illyria.nmsu.edu> ········@nmsu.edu (Tom Eskridge) writes:

>the ~V is not documented in either CLtL I or II.  Does anyone have any info on
>this? 
>tom eskridge

there is no ~V, however, V may be used as a prefix parameter.

p386 CLtL:
the V prefix parameter takes an argument from arguments as a parameter to
the directive.  ... This feature allows variable-width fields and the like.

If you were so disposed, you could use ~V,V,V,VA
--

-- jeff
seismo!godot.think.com!mincy

From: Mark Preece
Subject: Re: ~V directive in format statments
Date: Mon, 11 Feb 1991 22:43:04 +0000
Message-ID: <780@ministry.cambridge.apple.com>

In article <······················@illyria.nmsu.edu> ········@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.