Re: [classad-users] Constraint Question

[Alain Roy <roy@xxxxxxxxxxx>]

At 10:30 AM 1/18/2006 -0600, Matthew Farrellee wrote:
> ad1 = [A=1]
> ad2 = [A=2; B=3]
> ad3 = [A=4; C=5]
>
> It's possible to create a constraint that matches ad1 but not ad2: A=!
> =UNDEF && B==UNDEF, right?
You're mixing syntax for old and new ClassAds, but yes. In new 
ClassAds, you can write:
Requirements = A isnt defined && B is undefined;

In old classAds, you'll use =!= and =?= (not ==).

> What about a constraint matching ads that have only an A attribute.
> Can I do that without knowing about all possible attributes that
> might be in an ad?
There is no way to do that in the language--you'd have to have a code 
solution for that. It *might* be possible to write a user-defined 
function in the C++ implementation to do that, but I'm not sure off 
the top of my head.
-alain