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TraceInternal and OptionQ

• To: mathgroup at smc.vnet.net
• Subject: [mg8949] TraceInternal and OptionQ
• From: tburton at cts.com (Tom Burton)
• Date: Mon, 6 Oct 1997 01:59:18 -0400
• Organization: Brahea Consulting
• Sender: owner-wri-mathgroup at wolfram.com

Olivier Gerard recently mentioned the option "TraceInternal" to the
function "Trace". Wow! This is the first I've heard (seen) of this
option. So far, I cannot find it in the MMA2 or MMA3 books or in MMA3
on-line docs. Yet it seems very useful--perhaps essential, on occasion.
Is this an "undocumented" feature? Are users supposed to avoid it? If
so, what alternative is there?

Similarly, after reading about the function OptionQ in a third-party
book, I began using it extensively to screen for options in argument
lists, as in

myFunc[matrix_?MatrixQ, label_String, opts___?OptionQ] :=3D body

Recently, I noticed that the function "OptionQ" is similarly
undocumented. In this case, I note that the pattern "opts___Rule" seems
to perform the same function, perhaps a bit more elegantly, so I have
began using "opts___Rule" in place of "opts___?OptionQ". Can anyone see
a disadvantage to this substitution?

Thanks.
Tom