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From "Henri Biestro (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (JEXL-246) Intermittent ambiguous method invocation when processing assignOverload
Date Tue, 16 Jan 2018 19:41:01 GMT

     [ https://issues.apache.org/jira/browse/JEXL-246?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Henri Biestro resolved JEXL-246.
--------------------------------
    Resolution: Fixed

Uberspect on JexlArithmetic now properly sees all operator methods that are not mere overrides
of base implementation. For instance 'JexlOperator selfAdd(Object...' is now detected.

MethodKey has relaxed rules wrt ambiguity with nulls; if there are several applicable method
and one the parameter is null, if one applicable defines this parameter as an Object, no
ambiguity will be reported and that method will be chosen. In other words, when null is present
as argument, parameter of type Object is considered the best match (over more precisely typed
parameters).

src/main/java/org/apache/commons/jexl3/internal/introspection/MethodKey.java
src/main/java/org/apache/commons/jexl3/internal/introspection/Uberspect.java
src/test/java/org/apache/commons/jexl3/IssuesTest200.java
src/test/java/org/apache/commons/jexl3/SideEffectTest.java

Committed revision 1821295.

> Intermittent ambiguous method invocation when processing assignOverload
> -----------------------------------------------------------------------
>
>                 Key: JEXL-246
>                 URL: https://issues.apache.org/jira/browse/JEXL-246
>             Project: Commons JEXL
>          Issue Type: Bug
>    Affects Versions: 3.1
>            Reporter: Dmitri Blinov
>            Assignee: Henri Biestro
>            Priority: Minor
>             Fix For: 3.2
>
>
> Sometimes the simple operator like {code}z += 1{code} when {{z}} has not been defined
yet raises an exception {{org.apache.commons.jexl3.internal.introspection.MethodKey$AmbiguousException}}
with the following stack trace: 
> {quote}
> ambiguous method invocation: MyArithmetic.selfAdd(null, java.lang.Integer)
> org.apache.commons.jexl3.internal.introspection.MethodKey$AmbiguousException: null
> 	at org.apache.commons.jexl3.internal.introspection.MethodKey$Parameters.getMostSpecific(MethodKey.java:540)
> 	at org.apache.commons.jexl3.internal.introspection.MethodKey$Parameters.access$000(MethodKey.java:452)
> 	at org.apache.commons.jexl3.internal.introspection.MethodKey.getMostSpecificMethod(MethodKey.java:261)
> 	at org.apache.commons.jexl3.internal.introspection.ClassMap.getMethod(ClassMap.java:178)

> 	at org.apache.commons.jexl3.internal.introspection.Introspector.getMethod(Introspector.java:146)
> 	at org.apache.commons.jexl3.internal.introspection.MethodExecutor.discover(MethodExecutor.java:52)
> 	at org.apache.commons.jexl3.internal.introspection.Uberspect.getMethod(Uberspect.java:218)

> 	at MyUberspect.getMethod(MyUberspect.java:168)
> 	at org.apache.commons.jexl3.internal.introspection.Uberspect$ArithmeticUberspect.getOperator(Uberspect.java:413)
> 	at org.apache.commons.jexl3.internal.Operators.tryOverload(Operators.java:85) 
> 	at org.apache.commons.jexl3.internal.Operators.tryAssignOverload(Operators.java:118)

> 	at org.apache.commons.jexl3.internal.Interpreter.executeAssign(Interpreter.java:1292)

> 	at org.apache.commons.jexl3.internal.Interpreter.visit(Interpreter.java:1102) 
> ....
> {quote}
> The class MyArithmetic contains a couple of overloaded
> {{public JexlOperator selfAdd(T x, Object y)}} methods with the first argument being
the desired type {{T}} like {{Appendable}} or {{Collection}} for which the {{+=}} operator
is overloaded.
> Obviously in case where the first argument is null and the second argument is an Integer
it is not possible to differentiate between {{public JexlOperator selfAdd(Collection x, Object
y)}} and {{public JexlOperator selfAdd(Appendable x, Object y)}} but I wonder is there any
point in trying to perform {{selfAdd}} on the null variable? What questions me more is that
this error is intermittent and sometimes there is an exception and sometimes there is not,
so at the moment I have no test case to reproduce. So I think this is a bug.



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