Re: Re: Which, If and "neither True nor False"
- To: mathgroup at smc.vnet.net
- Subject: [mg9851] Re: [mg9728] Re: Which, If and "neither True nor False"
- From: Allan Hayes <hay at haystack.demon.co.uk>
- Date: Fri, 28 Nov 1997 05:36:06 -0500
- Sender: owner-wri-mathgroup at wolfram.com
Paul E Howland wrote:
> .......
> The most comprehensive implementation of Which (suggested in email to me
> by Robert Villegas of WRI ) would be to have a construct of the form:
> Which[test1, {action if True, action if Indeterminate},
> test2, {action if True, action if Indeterminate},
> ...
> True, default action
> ];
> which allows you to define an action to be carried out if a test returns
> Indeterminate. This action could be to continue to the next test.
Paul:
How about the following?
SetAttributes[Which2}, HoldAll];
Which2[c_, skp, skp, r__]:= Which2[r] Which2[c_, skp, u_, r__]:= If[c,
Which2[r], Which2[r], u] Which2[c_, t_,skp, r__]:= If[c, t, Which2[r],
Which2[r]] Which2[c_, t_, u_, r__]:= If[c, t, Which2[r], u];
Which2[d_]:= d
skp is the action of skipping to the next test.
Allan
Allan Hayes
Mathematica Training and Consulting
Leicester, UK
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk
voice: +44 (0)116 271 4198
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