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Re: TraceInternal and OptionQ

  • To: mathgroup at smc.vnet.net
  • Subject: [mg8995] Re: [mg8949] TraceInternal and OptionQ
  • From: Allan Hayes <hay at haystack.demon.co.uk>
  • Date: Tue, 7 Oct 1997 03:35:41 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

tburton at cts.com (Tom Burton)
[mg8949] TraceInternal and OptionQ
remarks on the lack of documentation of TraceInternal and OptionQ  
and aks why use ___?OptionQ in preference to ___Rule.

Tom:
(1) Yes, they could be better documented, but we can get at them:

Options[Trace]
{MatchLocalNames -> True, TraceAbove -> False,
  TraceBackward -> False, TraceDepth -> Infinity,
  TraceForward -> False, TraceInternal -> Automatic,
  TraceOff -> None, TraceOn -> None,
  TraceOriginal -> False}

?TraceInternal
"TraceInternal is an option for Trace and related functions which,  
if True or False, specifies whether to trace evaluations of  
expressions generated internally by Mathematica. The intermediate  
Automatic setting traces a selected set of internal evaluations  
including Messages and sets or unsetsof visible symbols."

?OptionQ
"OptionQ[e] returns True if e can be considered an option
or list of options, and False otherwise."

(2) As for ___?OptionQ compared with  ___Rule

 a ->b, a:>b and  {a ->b, a->b} both match the first but not the second 

I recommend ___?OptionQ

Allan Hayes
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk/training.html
voice:+44 (0)116 2714198
fax: +44 (0)116 2718642
Leicester,  UK


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