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https://issues.apache.org/jira/browse/DAFFODIL-2249?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Lawrence updated DAFFODIL-2249:
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Fix Version/s: (was: 3.0.0)
> refactor DSOM types to enable sealed classes/traits so case statements
> provide better warnings
> ----------------------------------------------------------------------------------------------
>
> Key: DAFFODIL-2249
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2249
> Project: Daffodil
> Issue Type: Improvement
> Components: Front End
> Affects Versions: 2.5.0
> Reporter: Mike Beckerle
> Priority: Major
>
> There are quite a few places where scala match-case logic is used in the
> daffodil schema compiler. This is typical of compilers, in that they often
> have algorithms that operate over a number of types that benefit from keeping
> the whole algorithm in one class.
> The scala compiler will produce valuable warnings that improve
> maintainability of the code if the types involved in the case analysis are
> sealed - that is, if the scala compiler knows the complete set of
> possibilities.
> The DSOM types can be refactored so that the primary traits/classes used in
> case statements are all in one file where they can all be sealed, enabling
> the scala compiler's checking.
> These classes/traits are large and rich, so their definitions do not all want
> to be centralized into that one file.
> Hence, each DSOM type that ultimately derives from SchemaComponent should be
> split into a "Primary" trait that lives in the existing file, and a part that
> lives in a new central file for the sealed traits/classes. Using ElementBase
> as an example, the centralized file will have
> {code}
> sealed abstract class ElementBase(....)
> extends Term(....)
> with ElementBasePrimaryMixin
> {code}
> And the existing ElementBase.scala file would have:
> {code}
> final trait ElementBasePrimaryMixin
> extends ... list of everything already in the extends of ElementBase....
> { self : ElementBase =>
> .... all existing contents of ElementBase class
> }
> {code}
> This enables us to also cleanup the schema compiler in that we can insure the
> traits/classes defined in the centralized file are all properly named so that
> those are the only traits/classes one uses in case statements. I.e., use of
> traits/classes whose names end in "...Mixin" would be exclusively in the
> extends-with clauses of trait/class definitions, and not in case analysis.
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