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https://issues.apache.org/jira/browse/DATAFU-50?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Philip (flip) Kromer updated DATAFU-50:
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Attachment: 0001-DATAFU-50-SimpleEvalFunc-should-extend-ContextualEva.patch
Decided to call the method 'onReady', because I don't think the user should be
any more interested in when or why it's called than "OK here's your chance".
* SimpleEvalFunc now extends ContextualEvalFunc (rather than
plain-old-EvalFunc), letting front end talk to back end
* ContextualEvalFunc has a hook method onReady(in_schema, out_schema) -- this
is sugar for UDFs that simply want an opportunity to capture or set values once
for a job, rather than legitimately wanting to override outputSchema().
* Updates AliasableEvalFunc to use onReady
> SimpleEvalFunc should extend ContextualEvalFunc, have good lifecycle hooks
> --------------------------------------------------------------------------
>
> Key: DATAFU-50
> URL: https://issues.apache.org/jira/browse/DATAFU-50
> Project: DataFu
> Issue Type: Improvement
> Reporter: Philip (flip) Kromer
> Labels: Utils
> Attachments:
> 0001-DATAFU-50-SimpleEvalFunc-should-extend-ContextualEva.patch
>
>
> Being able to squirrel away values frozen at frontend-launch-time is very
> handy.
> This does two things:
> * makes SimpleEvalFunc extend ContextualEvalFunc rather than
> plain-old-EvalFunc. This seems harmless and gains you all that power of
> Contextualism.
> * Adds a hook method "void schemaReadyHook(inputSchema,outputSchema)" to
> ContextualEvalFunc, called once the schemata are prepared. This acts as sugar
> for classes that want to set properties at front-end time to be used at later
> points but which, like most SimpleEvalFunc's, want nothing to do with schema
> calculation. In ContextualEvalFunc it does nothing; subclasses may override
> it and if so must call super. schemaReadyHook().
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