Re: [eclipse-users] Long parameter lists

Hi Vivek,

Vivek Balaraman wrote:
> My constraint computation on a design problem requires anywhere from 
> 40-50 parameters. The constraint program itself will be embedded in a 
> java program.
>  
> What would be the most scalable and robust way of passing and 
> returning such a large number of values to the program?
I would suggest that you set up two peer queues (one to-eclipse, one 
from-eclipse), to pass the data between Java and ECLiPSe. You could then 
pass the data as pairs of parameter name and value  using the queue. 
Using the parameter name avoid the problem of scheme that relies on the 
position of the data to determine which parameter it is for, which is 
easy to get wrong, and hard to modify.

The high-level generic interface paper I mentioned previously posting to 
this mailing list, available at:

http://eclipse.crosscoreop.com/reports/index.html

has an example of using the peer queues (although it is described mainly 
using Tcl/Tk as the external language, the example applies equally well 
to Java as the external language). There is also an example in the Java 
examples directory: EclipseMapColourer.java.

>  
> a) Both calling program and constraint program write / read to DB or 
> some such persistent storage accessible by both programs
This is probably not as good a solution as using peer queues, but you 
can use MySQL as the database with lib(dbi) for this. If you do want to 
use persistent storage instead of peer queues,  you are probably better 
off using files, and passing the file name between ECLiPSe and Java.
> b) As part of the parameter list
It is probably not a good idea to use RPC to do this -- you should avoid 
constructing/parsing large complex ECLiPSe data structures on the Java 
side.

Cheers,

Kish
>  
> Thanks
>  
> Vivek Balaraman
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