Optional
- To: mathgroup at smc.vnet.net
- Subject: [mg33689] Optional
- From: Ben Langton <ben at quickmath.com>
- Date: Sat, 6 Apr 2002 00:49:16 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hi all,
I am having a problem with the Optional function which I have reduced to the
following snippet of code :
f // Clear;
f[Optional[index : {_Integer ...}, {1}]] := index;
f[]
My understanding of the Optional command is that the function f should
accept a list of zero or more integers as its argument or, if that is
missing, use the default value of {1}.
Under version 3, f[] (f with no arguments) returns {1}, as I would expect,
yet under version 4.1 it returns the function evaluated.
Can anyone shed any light on why this code acts differently under the two
different versions? What can I do to make it work as expected under version
4.1?
Many thanks,
Ben Langton