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Posted to notifications@groovy.apache.org by "Eric Milles (Jira)" <ji...@apache.org> on 2026/05/23 13:48:00 UTC

[jira] [Commented] (GROOVY-12024) Subscript operator for Map has unexpected behavior when key is 'properties'

    [ https://issues.apache.org/jira/browse/GROOVY-12024?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18083070#comment-18083070 ] 

Eric Milles commented on GROOVY-12024:
--------------------------------------

The subscript operator is not synonymous with get(key). It maps to getAt, which has a few overloads. There is another issue that discusses the parameter distance and receiver distance. Short version is a new getAt(Map,String) overload should be created. 

> Subscript operator for Map has unexpected behavior when key is 'properties'
> ---------------------------------------------------------------------------
>
>                 Key: GROOVY-12024
>                 URL: https://issues.apache.org/jira/browse/GROOVY-12024
>             Project: Groovy
>          Issue Type: Bug
>            Reporter: David Costanzo
>            Priority: Minor
>
> The subscript operator has strange behavior for Map when the key is 'properties'.  Instead of accessing the value associated with that key, it accesses a read-only Map object.
> This behavior changed between Groovy 3 and Groovy 5.  My expectation is that the subscript operator can access values for a key named 'properties', as it did in Groovy 3.
> *Steps to Reproduce:*
> In groovysh 5, the subscript operator references the system-provided, read-only map.
>  
> {code:java}
> groovy> map = ['properties': 1]
> groovy> map['properties']
> [:]
> groovy> map['properties'] = 2
> ReadOnlyPropertyException: Cannot set read-only property: properties for class: java.util.LinkedHashMap{code}
>  
> In groovysh 3, the subscript operator references keys of the user-created map.
>  
> {code:java}
> groovy:000>  map = ['properties': 1]
> ===> [properties:1]
> groovy:000> map['properties']
> ===> 1
> groovy:000> map['properties'] = 2
> ===> 2{code}
>  
> I don't know if this is intentional, but I couldn't find a reference to in the documentation.  On [https://docs.groovy-lang.org/latest/html/documentation/#subscript-operator] it says that the subscript operators is a shorthand for getAt() and setAt().  On [https://docs.groovy-lang.org/latest/html/groovy-jdk/java/util/Map.html#getAt(java.lang.Object)] it does not mention that "properties" can't be used as a key.
> In my view, this is either a code bug (an internal implementation detail is being exposed beyond it's intended scope) or a doc bug (the subscript operator or Map.getAt() should mention the reserved system key named "properties").
> *Impact:*
> This creates the potential for hidden bugs.  For example, I have a script that manages some metadata for internal libraries using a map keyed by the library name.  The script  appears to work correctly, but then I add a library named "properties" and the script fails to work.  (This is not theoretical, this is what actually happened to me).
>  



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