Re: Mathematica question (another one)
- To: mathgroup at smc.vnet.net
- Subject: [mg5751] Re: [mg5737] Mathematica question (another one)
- From: Allan Hayes <hay at haystack.demon.co.uk>
- Date: Tue, 14 Jan 1997 10:42:29 -0500
- Sender: owner-wri-mathgroup at wolfram.com
Gadi Oron <oron at tremois.pmmh.espci.fr>
[mg5737] Mathematica question (another one)
writes
>>>>>>>>>>>
>How should i define a function that has an optional argument with
>certain form, let me explain:
>Suppose that a function has to receive an OPTIONAL list of rules
>that takes the deafault value {}.
>
>I've tried :
>
>func[sub:{___Rule}:{}]:=...
>
>But it does not work.
Gadi:
f[Optional[sub:{___Rule} ,{}]]:= A[sub]
is OK on V3.0 but not on V2.2.
However
f[sub:{___Rule}:{}]:= A[sub]
is not accepted as proper input in V3.0 and, does not work in V2.2.
You might like to try ___?OptionQ instead of ___Rule.
?OptionQ
OptionQ[e] returns True if e can be considered an option or list of
options, and False otherwise.
Allan Hayes
hay at haystack.demon.co.uk
http://haystack.demon.co.uk