gortiz commented on PR #10361:
URL: https://github.com/apache/pinot/pull/10361#issuecomment-1467570156
> is there any reason why RegexpLike and FST-Based factories not part of the
visitor pattern change?
Just because I don't need it right now. I didn't iterate over all predicates
to look for useful cases. In order to do not add features we may not use, I
thought it would be better if we add them whenever we need them. But I can try
to do it.
> DataType visitor tests are not showing exactly how this will be useful yet.
Given that DataType is an enum, we can use a switch and DataTypeVisitor is
not that useful. I'm using it in a situation where the code in the switch
depends on some context, so I do something like:
```java
DataTypeVisitor<R> visitor;
if (condition.is.fulfilled) {
visitor = new VisitorInCase1;
} else {
visitor = new VisitorInCase2;
}
R result = dataType.accept(visitor)
```
But I can use `Function` instead:
```java
Function<DataType, R> fun;
if (condition.is.fulfilled) {
fun = dt -> {
switch (dt) {
case INT: return X1;
case DOUBLE: return Y1;
default: return Z1;
}
};
} else {
fun = dt -> {
switch (dt) {
case INT: return X2;
case DOUBLE: return Y2;
default: return Z2;
}
};
}
R result = fun.apply(dataType);
```
The main difference is that the switch will not be protected by the compiler
in case a new data type is added, but given that it isn't a very common change,
I think I'm going to follow the second approach in order to create less
confusion in this PR.
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