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Groups > comp.soft-sys.math.mathematica > #16487

Re: Default value in pattern matching

From Yi Wang <tririverwangyi@gmail.com>
Newsgroups comp.soft-sys.math.mathematica
Subject Re: Default value in pattern matching
Date 2014-01-28 11:05 +0000
Message-ID <lc82u0$3u8$1@smc.vnet.net> (permalink)
References <lbdjjl$58f$1@smc.vnet.net>
Organization Time-Warner Telecom

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Actually, the property I looked after is not that Plus has a default value (though it is an insignificant part of the story), but that Plus has attribute OneIdentity, which affects pattern matching. 

SetAttributes[myPlus, OneIdentity]

Default[myPlus] = 0;
a /. {myPlus[a, b_.] -> "matched"}

Out[] = "matched"

The example given here is not exactly as the one in my question. But this is enough for my purpose.

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Default value in pattern matching Yi Wang <tririverwangyi@gmail.com> - 2014-01-18 10:04 +0000
  Re: Default value in pattern matching Yi Wang <tririverwangyi@gmail.com> - 2014-01-28 11:05 +0000

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