Look at the string in which it returns.
":DATA1,:DATA2,:DATA3"
Try running just that without the quotes, you'll get the same thing.
If you have column names as strings, you can do something like this.
Names default to here(1);
dt = New Table( "Example",
Add Rows( 1 ),
New Column( "Data1", Set Values( [1] )),
New Column( "Data2", Set Values( [2] )),
New Column( "Data3", Set Values( [3] )),
);
// list of column names as strings
list = dt << Get Column Names("string"); // {"Data1", "Data2", "Data3"}
SumExpr = Expr(Sum());
for(i=1, i<=nitems(list), i++,
insert into(SumExpr, Column(dt, list[i]));
);
// see what the sumExpr looks like
show(nameexpr(sumExpr));
// then you have to do some substitute in order to actually get it to run
just_for_show = EvalExpr(
dt << New Column("Another Data", Formula(Expr(nameexpr(SumExpr))));
);
show(nameexpr(just_for_show));
just_for_show();// this will actually run the expression you just created.
// or you could use the list in Sum Directly.
// list of column names as references
list = dt << Get Column Names();
list=list[1::3];
// can do a list directly in Sum()
// should still substitute it in so it's no dependant on then list variable
just_for_show =Substitute(
Expr(
dt << new Column("Yet Another Data", Formula(Sum(DV_LIST)))
),
Expr(DV_LIST), list
);
show(nameexpr(just_for_show));
just_for_show(); // actually evaluates again.
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