Re: Problem combining patterns
- To: mathgroup at smc.vnet.net
- Subject: [mg119271] Re: Problem combining patterns
- From: Leonid Shifrin <lshifr at gmail.com>
- Date: Sat, 28 May 2011 07:19:07 -0400 (EDT)
You can do
ClassPattern[] := _?(Length[#] === 1 &);
or
ClassPattern[] := _ [ _ ]
Regards,
Leonid
On Fri, May 27, 2011 at 2:12 PM, Rui <rui.rojo at gmail.com> wrote:
> Hey people.
> I want to have an expression that evaluates to a pattern. Imagine
> something simple
>
> ClassPattern[]:=HoldPattern[i_/;Length[i]===1];
> So far so good. But then I'd like to use it in compound expressions
> like
>
> MatchQ[{b[3], c[5]}, {ClassPattern[], ClassPattern[]}]
>
> When I do so, the label "i" inside the pattern is treated as the same
> in both ClassPatterns, so I get false. But I wanna get True in cases
> like the one before
>
> Any ideas?
>
>