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Re: destructuring-bind for subset of plist


From: Barry Margolin
Subject: Re: destructuring-bind for subset of plist
Date: Wed, 25 May 2016 21:30:56 -0400
User-agent: MT-NewsWatcher/3.5.3b3 (Intel Mac OS X)

In article <address@hidden>,
 Sam Halliday <address@hidden> wrote:

> Hi all,
> 
> This causes an error
> 
>   (cl-destructuring-bind
>       (&key a b)
>       '(:a "foo" :b 13 :c "bar")
>     (list a b))
> 
> because the :c key/value is not handled in the pattern match.
> 
> Often I find myself wanting to extract some subset of keys/values from a 
> plist, but cl-destructuring-bind isn't appropriate because of this 
> limitation.
> 
> Is there a way to make cl-destructuring-bind simply ignore unmatched keys in 
> the EXPR? I'm not sure what the official common lisp behaviour is supposed to 
> be here, is the error in the spec?
> 
> Note that the dash library has some support for a similar destructuring with 
> -let, but that requires some boilerplate to assign a symbol to each key.
> 
> Best regards,
> Sam

In CL you'd use (&key a b &allow-other-keys)

-- 
Barry Margolin, address@hidden
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***


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