[jira] [Assigned] (IGNITE-15564) [Ignite 3] Properly inject names into named list elements

["Kirill Tkalenko (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-15564?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kirill Tkalenko reassigned IGNITE-15564:
----------------------------------------

    Assignee: Kirill Tkalenko

> [Ignite 3] Properly inject names into named list elements
> ---------------------------------------------------------
>
>                 Key: IGNITE-15564
>                 URL: https://issues.apache.org/jira/browse/IGNITE-15564
>             Project: Ignite
>          Issue Type: Improvement
>    Affects Versions: 3.0.0-alpha2
>            Reporter: Ivan Bessonov
>            Assignee: Kirill Tkalenko
>            Priority: Major
>              Labels: iep-55, ignite-3
>
> h3. Problem
> Current design of named lists has a flaw that is best shown in classes like "TableConfigurationSchema". It's the field called "name". Simple table configuration would look like this (prefix "table.tables" looks bad BTW):
> {code:java}
> table.tables : {
>     foo : {
>         name = foo,
>         etc...
>     }
> }{code}
> Table name must be duplicated and I actually doubt that we validate names equality. Same applies to columns and indexes. There's probably more, I didn't check.
> Obviously, developers want to access named list element name inside of the element itself. And there's no API for that.
> h3. Approach
> Proper solution would be annotating name fields:
> {code:java}
> @Config
> public class TableConfigurationSchema {
>     @InjectedName // temporary title, maybe there are better options
>     public String name = "default";
>     ...
> }{code}
> Injected name must be a string. It's treated like "@Value" field BUT has no "update" method associated with it. Basically, name is considered immutable and "explicitly uninitializable" in this context. So how do you initialize it then?
>  * if schema is used as a named list - name is passed into "create*"/"rename" methods. Field is automatically updated after that.
>  * if schema if used as a regular config value, we have two options:
>  ** generate special extended interfaces that will in fact have setters for names. These will only be used for "non-named-list" values;
>  ** always use default value provided in either schema itself (as in example) or in "@Value(name = "default") if it makes any sense. This option looks better for me and it's easier to implement.
> h3. Implementation notes
> Compile-time code generation is easy, just reuse already existing methods and add few "if" clauses.
> I don't think that methods like "traverse*" or "construct*" should process name fields. So there's a filtering to be done in ConfigurationAsmGenerator.
> "NamedConfigValue#syntheticKeyName" should probably be removed. Instead we should use injected field name or just "name" if there's none. Otherwise there will be a confusion.
> All classes that use constant "NamedListNode#NAME" are a subject to modification. There's a high chance that they will inject values for annotated fields. Maybe we need a new method in "InnerNode" for this, it's not clear yet.
> Classes that implement ConfigurationSource should be carefully examined as well, especially HOCON* ones.
>  



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