Re: undocumented function StringQ
- To: mathgroup at smc.vnet.net
- Subject: [mg47804] Re: undocumented function StringQ
- From: Harold.Noffke at wpafb.af.mil (Harold Noffke)
- Date: Tue, 27 Apr 2004 04:47:43 -0400 (EDT)
- References: <c6d8dd$jh6$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
$Version "5.0 for Microsoft Windows [2000] (November 18, 2003)"
Ingolf:
Robert Villegas' original code ...
Block[{$Urgent = {}},
Select[Names["System`*"],
(Information[#]; Not @ StringQ[
MessageName @@ Append[ToHeldExpression[#], "usage"]
])&
]
]
can be revised to remove Information[#] and $Urgent={}. This produces
a Block which gives identical results ...
Block[{}, Select[ Names["System`*"],
(!StringQ[MessageName @@ Append[ToHeldExpression[#],"usage"]])& ]
]
It is use of the $Urgent={} expression which puzzles me. I don't see
what the programmer's intent is in doing this. MathBook says ...
$Urgent gives the list of files and pipes to which urgent output
from Mathematica is sent.
In[117]:=
$Urgent//FullForm
Out[117]//FullForm=
List[OutputStream["stdout",1]]
In normal programming, what is the $Urgent={} expression supposed to
provide for us? How is it supposed to be used?
Thanks.
Harold