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From Doug Cutting <cutt...@apache.org>
Subject Re: schema defaults not reflected in generated objects (1.3.2)
Date Thu, 10 Jun 2010 18:49:31 GMT
On 06/10/2010 09:27 AM, Scott Carey wrote:
> I propose:
> * We use getters/setters, and allow setters and constructors to be
> package protected with an option so the objects can be safely passed
> around outside the package without stateful wrapper objects.  Users
> can write factory methods or other static helper methods to abstract
> away as much as they would like from there.
> * Setters should not allow invalid data to be set.

I'd be okay with these changes.  +1

> * Provide some built-in mechanism to resolve unions on a read and
> verify them on a write.  Perhaps a inner static enum for each union,
> and a getter for each branch.

So a schema like:

{"type":"record", "name":"Foo", "fields":[
   {"name":"bar", "type":["int", "float"]}]}

might generate something like:

public class Foo {
   public enum BarType { INT, FLOAT }
   private BarType bar$Type;
   private Object bar;
   public void setBar(int value) { bar = value; bar$Type = INT; }
   public void setBar(float value) { bar = value; bar$Type = FLOAT; }
   public int getBar$Int() {
     if (bar$Type != INT) throw new ...;
     return (int)bar;
   }
   public float getBar$Float() {
     if (bar$Type != FLOAT) throw new ...;
     return (float)bar;
   }
}

Is that the sort of thing you have in mind?  I've added dollar signs to 
avoid potential conflicts, e.g., if the user had a field named 'barType' 
or 'barInt'.  I think its best to always add the dollars, since 
otherwise it could get awkward if a field named 'barInt' were added later.

> * Unions with one type and NULL should not translate to Object, but
> rather be that type and allow null.

That's already the case, no?

Also, you didn't provide a proposal for constructors, yet, right? 
Perhaps all of the setters could be on a generated builder class, with 
an instance only returned when it's completely populated?

Doug

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