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<== Date ==> <== Thread ==>
Subject: Re: CA wishlist :)
From: "J. Lewis Muir" <[email protected]>
To: [email protected]
Date: Wed, 12 Dec 2007 15:07:22 -0500
On 12/12/07 12:43 PM, Jeff Hill wrote: 
Wouldn't it be nice to specify the EPICS_CA_* values firstly through
functions in the library rather than environment variables only.
And then secondly on a per-connection basis.
So you can have seperate setup for every PV connection. ?


One benefit of EPICS environment variables is their ability to make a site
wide default, and to configure the CA aspects of multiple tools with a
common interface - albeit a rather primitive one.

I suppose that one _could_ set them programmatically by calling putenv(),
but most of them _would_ need to be set before initializing the CA context.

CA's configuration was designed a long time ago so perhaps there is now an
open source library for configuration that we should use in the future. We
would of course remain backwards compatible to the past environment variable
based configuration if the new configuration interface isn't used. Perhaps
we should look at the XML related libraries.

I'm not against a configuration file type approach, but I'd like to note that for me the environment variables work just fine. They are a simple way to pass parameters to a program. To me, managing the environment variables is fairly simple.

For example, on modern Linux distributions, there's an /etc/profile.d directory where I can put an epics.csh and epics.sh that sets up the environment variables the way I want for the computer. User's can override these in their own environment if they want to.

Or if there's a need to support a number of environments, it's easy to put the commands to set the environment variables into files and then just source the file containing the desired environment configuration.

It's also easy to write a shell script that sets up the environment and then invokes whatever program with a correctly set up environment.

So I completely understand that others have different requirements than me, and maybe environment variable configuration doesn't work well for some situations, but I just wanted to note that it works fine for me.

Lewis

--
J. Lewis Muir
Software Engineer
CARS/IMCA-CAT
References:
CA wishlist :) Heinrich du Toit
RE: CA wishlist :) Jeff Hill
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