[Bug-jel] Data type of compiled expressions

[Mike Squance]

Hi,

First, let me say that I've been extremely happy with JEL and I hope it
continues to be supported.

I'm having a bit of trouble with the data type of expressions that I suspect
is a limitation of the software, but I thought I'd ask anyways.

I rely on the getType() result to validate whether an expression has been
entered correctly with respect to the data type that the expression is
supposed to be producing. For example:

  There are 2 measurements defined:
    RAW1 of type Integer
    RAW2 of type Integer

  A derived measurement is defined:
    DERIVED1 of type Integer

  An expression is written to derive DERIVED1 from the available
measurements. 

  I look at the result of getType() to ensure that the result of the
expression for DERIVED1 is of type Integer.

In general, with expressions like "RAW1 + RAW2", "RAW1 + 10", this works
fine. I get Integer as the resulting data type. However, with an expression
"RAW1" or "(RAW1 > RAW2)?(RAW1):(RAW2)", I get Object as the resulting data
type. I know that I can do "RAW1+0" to work around this, but this is not
very desirable.

Here is a bit of code, based on the YourTestBed example. The DVResolver was
updated to support Integer.

        resolver.addProperty("RAW1", new Integer( 10 ) );
        resolver.addProperty("RAW2",new Integer( 3 ) );
        
        expr=gnu.jel.Evaluator.compile("RAW2",lib);
        System.out.println("DATATYPE = " +expr.getType() );
        System.out.println("RAW2="+expr.evaluate(context));

        expr=gnu.jel.Evaluator.compile("(1>0)?(RAW1):(RAW2)",lib);
        System.out.println("DATATYPE = " +expr.getType() );
        System.out.println("MYRESULT = " +expr.evaluate(context) );

First, is this a bug? If not, can you suggest a better alternative than the
"+0" approach?

Thanks for any help,
Mike.