Re: dbLoadRecord or dbLoadTemplate

[Andrew Johnson <anj@aps.anl.gov>]

Ralph Lange wrote:
> > Personally, I would even go as far as setting dbLoadTemplate on the
> > IOC to "deprecated" status. I don't see an advantage over host side
> > expansion.

To which Mark Rivers replied:
> I strongly disagree with this.  Doing host-side expansion requires an
> EPICS build system.

... which just goes to show how being flexible makes the EPICS community 
bigger and better.  We're not going to deprecate dbLoadTemplate() since 
it is essential to a significant part of our user-base, but obviously 
not to all sites.

Emmanuel Mayssat asked:
> I like the dbLoadTemplate
> because of the clarity, but then for each device instantiation you
> need to create a complete substitution file.  Is there a way to do
> something like this: dbLoadTemplate(file.sub,"deviceName=$(DEVN)") 
> Where the db files is generated and then parsed once again with macro
> provided in command line?  

Not at the moment, although it should be possible to do something like 
that if there is sufficient demand or someone wants to just implement 
it, i.e. allow additional macros to be provided on the dbLoadTemplate 
command line that would be included in the list of macros expanded in 
the template.  The relevant code is in base/src/dbtools/dbLoadTemplate.y

There is an additional trick both dbLoadRecords() and dbLoadTemplate() 
already do that may not be well documented, although I'm not sure that 
it will help you: File pathnames given in a .substitutions file or in 
include statements in a .db file will also have environment variable 
macros expanded.  This only applies to the file path/name though, not to 
the contents of the files themselves, and the values are taken from the 
environment variables at the time the file is loaded.

- Andrew
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