On 06/07/2010 01:53 PM, Bill de hOra wrote:
I.m wondering if I'm missing an incantation for 'compile schema/protocol' in Avro tools to handle defaults. Given this schema,
In Avro, default values are used by a reader when a writer's schema lacks a field. This permits one to add a new field and still process data written before that field was added, provided one specifies a default value for the new field. Similarly, if one removes a field, older code may still process the data, provided it has a default value.
This is related but not the same as the default value for a Java instance. When one manually specifies a default value for a field in Java, one does not do this not primarily in order to future-proof the class, but typically so that one can avoid having to explicitly set the value somewhere else. What both concepts have in common is that they permit a developer to provide a reasonable value to be used when no more specific value is known.
So it might be a useful feature if Java instance default values were acquired from the schema. For one thing, folks seem to expect it. But, from Avro's perspective, I don't think it's a bug.
Does that make sense? Doug
