Beware fcn[a_:0, x ___]
- To: mathgroup at smc.vnet.net
- Subject: [mg9852] Beware fcn[a_:0, x ___]
- From: bmarks at helix.nih.gov (William B. Marks)
- Date: Fri, 28 Nov 1997 05:36:07 -0500
- Sender: owner-wri-mathgroup at wolfram.com
It seems reasonable to want to say fcn[a_:0, opts___?OptionQ] := a for example. But it doesn't work: fcn[o->"o"] gives o->o instead of 0. Instead one can say fcn[a_:0, opts__?OptionQ] := a Then fcn[o->"o"] gives 0 as it should. However fcn[] gives fcn[] whereas what we wanted originally was for fcn[] to give 0. But if you never want to say fcn[], but only fcn[1], fcn[1, o->"o"] and fcn[o->"o"], for example, the second form seems to be the best choice. What do you think? Bill Marks