Re: [Sbcl-help] read-from-string

[Brian M. <br...@ma...>]

On 09/19/2010 09:25 PM, Jerry James wrote:
> With SBCL 1.0.38, on an x86_64 Fedora 13 machine:
>
> * (read-from-string "Is it nil or t?" :start 6 :end 9)
>
> IS
> 3
>
*snip*
>
> I expected that to mean that only the characters between :start and
> :end would be examined.  Yet GCL 2.6.8pre, ECL 10.4.1, and Clisp 2.47
> all behave the same way on this machine, so ... what am I missing?

You're missing the wonderfully nonintuitive interaction between 
&OPTIONAL and &KEY. In your call, :START is taken as the value of 
ERROR-P, and 6 as the value of EOF-ERROR. Try this instead:

(read-from-string "Is it nil or t?" t nil :start 6 :end 9)
--
Brian Mastenbrook
br...@ma...
http://brian.mastenbrook.net/