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Re: Calling Install[] from packages

• To: mathgroup at smc.vnet.net
• Subject: [mg39963] Re: [mg39929] Calling Install[] from packages
• From: "Y.A.Tesiram" <yas at pcomm.hfi.unimelb.edu.au>
• Date: Thu, 13 Mar 2003 03:02:58 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,
You could use Links[] to show you a list of all LinkObjects. Then run a
test to see if your session is running. You could use something like,

runAtest = StringMatchQ[Links[][[#]]//ToString,
"LinkObject[theprogram*]"]&/@Range[Length[Links[]]];

If there is a match in runATest, there will be a True returned. You can
use this condition to skip the installation step. If there are no True's
then run Install["theprogram"]

Yas


On Wed, 12 Mar 2003, Lawrence A. Walker Jr. wrote:

> Hi group:
>
> Todd Gayley's Mathlink tutorial is very helpful.  Mr. Gayley has
> explained the advantages and disadvantages of either (1) package code
> de-embedded in external (Mathlink'd) programs, or (2) calling external
> programs from within the package (*.m).
>
> I chose the latter in my present project.  I have encountered a
> situation when package A runs package B via the Need[] command. Package
> B then links to the external program C.  Since package B is ran
> automatically, a user could attempt to run package B again.  The context
> handling functions appears to work ok in this case. However, a duplicate
> link of the external program is setup.  In other words, Install[] is ran
> again.  I desire that package B test to see if a link to the external
> program is already set up.  If it is then don't install the external
> program.
>
> Does anyone know of a way to handle the situation so that external
> programs are linked to as needed?
>
> Thanks,
> Lawrence
>
> --
> Lawrence A. Walker Jr.
> http://www.kingshonor.com
>
>