Using enum values to represent binary operators (or functions)
- by Bears will eat you
I'm looking for an elegant way to use values in a Java enum to represent operations or functions. My guess is, since this is Java, there just isn't going to be a nice way to do it, but here goes anyway. My enum looks something like this:
public enum Operator {
LT,
LTEQ,
EQEQ,
GT,
GTEQ,
NEQ;
...
}
where LT means < (less than), LTEQ means <= (less than or equal to), etc - you get the idea. Now I want to actually use these enum values to apply an operator. I know I could do this just using a whole bunch of if-statements, but that's the ugly, OO way, e.g.:
int a = ..., b = ...;
Operator foo = ...; // one of the enum values
if (foo == Operator.LT) {
return a < b;
}
else if (foo == Operator.LTEQ) {
return a <= b;
}
else if ... // etc
What I'd like to be able to do is cut out this structure and use some sort of first-class function or even polymorphism, but I'm not really sure how. Something like:
int a = ..., b = ...;
Operator foo = ...;
return foo.apply(a, b);
or even
int a = ..., b = ...;
Operator foo = ...;
return a foo.convertToOperator() b;
But as far as I've seen, I don't think it's possible to return an operator or function (at least, not without using some 3rd-party library). Any suggestions?
