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MathGroup Archive 2003

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Re: Unevaluated

  • To: mathgroup at
  • Subject: [mg44472] Re: [mg44465] Unevaluated
  • From: Anton Antonov <antonov at>
  • Date: Wed, 12 Nov 2003 08:01:23 -0500 (EST)
  • References: <>
  • Sender: owner-wri-mathgroup at

Hans-Peter Kunzle wrote:

>I was trying to make a function like 'tPrint[x___]' that would act
>like Print if some global variable Testing was True and do nothing
>if Testing was False. This would allow me to simply add or delete
>the 't' to individually turn on or off some tracing. It would
>be easier than to comment or uncomment the Print statements each
>But when I tried
>	tPrint[Unevaluated[x___]]:= If[Testing,Print[x]]
>I found, using TracePrint, that 'x' gets evaluated each time whether
>or not Testing is True.
>Maybe I do not understand properly how Unevaluated operates.
>Is there a way to do what I want?
>Any help is appreciated.
If I understand your question correctly, using the attribute HoldAll 
will do the job.

Anton Antonov
Wolfram Research, Inc.

  • References:
    • Unevaluated
      • From: Hans-Peter Kunzle <>
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