Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 28 Jan 2005 14:38:15 -0600

Emmanuel Mayssat wrote:

I use "dbLoad" files such as this one:

<snip>
Now, I would like to include in my dbl files a command that says:
If this variable is not set, then set it to this value.

This technique appears to be somewhat fragile (meaning you must be
careful if you decide to use it). It's probably fine if you have a
small number of .dbl files and can keep track of all the variables that
each one needs, but what happens if you should re-use a variable name
(with different default values) in two different dbl files? The first
dbl file would set the value it wants as the default, but the second
file would always see the earlier file's default setting (because the
variable was never unset), even if the user really wanted to use the
second dbl file's default. Swapping the order in which you execute the
two dbl files would change what is loaded into the database!
I would suggest that you require that the parent script must set *all*
parameters that a dbl file relies on itself, or load a single default
settings file early on like Eric suggested.
- Andrew
--
Dear God, I didn't think orange went with purple until I saw
the sunset you made last night.  That was really cool. - Caro

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System