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https://issues.apache.org/jira/browse/AVRO-530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17563891#comment-17563891
]
Kalle Niemitalo commented on AVRO-530:
--------------------------------------
Example:
{code:json}
{
"type":"record",
"name": "Main",
"fields":[
{
"name":"f1",
"type":"Sub"
},
{
"name":"f2",
"type":{
"type":"enum",
"name":"Sub",
"symbols":["OPEN","CLOSE"]
}
}
]
}
{code}
Transforming that to Parsing Canonical Form should result in:
{code:json}
{"name":"Main","type":"record",fields":[{"name":"f1","type":{"name":"Sub","type":"enum","symbols":["OPEN","CLOSE"]}},{"name":"f2","type":"Sub"}]}
{code}
rather than the use-before-define:
{code:json}
{"name":"Main","type":"record",fields":[{"name":"f1","type":"Sub"},{"name":"f2","type":{"name":"Sub","type":"enum","symbols":["OPEN","CLOSE"]}}]}
{code}
> allow for mutual recursion in type definitions
> ----------------------------------------------
>
> Key: AVRO-530
> URL: https://issues.apache.org/jira/browse/AVRO-530
> Project: Apache Avro
> Issue Type: Improvement
> Components: spec
> Affects Versions: 1.3.2
> Reporter: Jeff Hodges
> Priority: Major
>
> Suppose you have these two types in your protocol:
> {code}
> {"name": "User", "type": "record", "fields": [{"name": "current_status",
> "type": "Status"}]}
> {"name": "Status", "type": "record", "fields": [{"name": "author", "type":
> "User"}]}
> {code}
> This will raise an error! The current workaround is to define one of them at
> their first usage. Like:
> {code}
> {"name": "User", "type": "record", "fields": [{"name": "current_status",
> "type": {"name": "Status", "type": "record", "fields": [.. lots of fields
> ...]}]}
> {code}
> But this is incredibly unwieldy. It would be really nice for the spec to
> require all the parsers to allow for mutual recursion, instead. It could be
> done by implementing a two-pass parser. One pass to acquire names referenced,
> and a second to fill in those names with their appropriate references.
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