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https://issues.apache.org/jira/browse/GROOVY-7772?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

UEHARA Junji updated GROOVY-7772:
---------------------------------
    Description: 
Groovy's operator .& for method is similar functionality to Java8's method 
reference operator ::.

||No.||lhs||rhs||meaing of Groovy's .& (Closure) ||meaning of java8's :: 
(FunctionalInterface)||
|1|instance|instanceMethod| { ..args -> instance.instanceMethod(args) | same as 
groovy |
|2|Class|staticMethod| { ..args -> Class.staticMethod(args) | same as groovy |
|3|instance|staticMethod| ERROR groovy.lang.MissingMethodException: | Error 
same as groovy (compile error) |
|4|Class|instanceMethod|error| Function<RetType,Class,Args..>, where method 
instance method of Class which is declared as ```RetType instanceMethod(Args..) 
{...}```. In other words it is interpreted as a function which takes LHS Class 
as the first parameter which additionally inserted to the method.)|

IMHO, i'd like to propose to change the No 4 pattern semantics of groovy  same 
as Java 8 's. Because:

 * You can do:
{code}
["a,b,c"].collect ( String.&toUpperCase )
{code}

* Can have correspond operator to java8's ::. which is understandablea and 
needed for Java programmers.


  was:
Groovy's operator .& for method is similar functionality to Java8's method 
reference operator ::.

||No.||lhs||rhs||meaing of Groovy's .& (Closure) ||meaning of java8's :: 
(FunctionalInterface)||
|1|instance|instanceMethod| { ..args -> instance.instanceMethod(args) | same as 
groovy |
|2|Class|staticMethod| { ..args -> Class.staticMethod(args) | same as groovy |
|3|instance|staticMethod| ERROR groovy.lang.MissingMethodException: | Error 
same as groovy (compile error) |
|4|Class|instanceMethod|error| Function<RetType,Class,Args..>, where method 
instance method of Class which is declared as ```RetType instanceMethod(Args..) 
{...}```. In other words it is interpreted as a function which takes LHS Class 
as the first parameter which additionally inserted to the method.)|

IMHO, No 4. is useful.
 * You can do:
{code}
["a,b,c"].collect ( String.&toUpperCase )
{code}

* Can have correspond operator to java8's ::. which is understandablea and 
needed for Java programmers.



> Class.&instanceMethod had better to have same meaning of 
> Class::instanceMethod of Java8
> ---------------------------------------------------------------------------------------
>
>                 Key: GROOVY-7772
>                 URL: https://issues.apache.org/jira/browse/GROOVY-7772
>             Project: Groovy
>          Issue Type: Improvement
>          Components: groovy-runtime
>    Affects Versions: 2.4.6
>            Reporter: UEHARA Junji
>            Priority: Minor
>
> Groovy's operator .& for method is similar functionality to Java8's method 
> reference operator ::.
> ||No.||lhs||rhs||meaing of Groovy's .& (Closure) ||meaning of java8's :: 
> (FunctionalInterface)||
> |1|instance|instanceMethod| { ..args -> instance.instanceMethod(args) | same 
> as groovy |
> |2|Class|staticMethod| { ..args -> Class.staticMethod(args) | same as groovy |
> |3|instance|staticMethod| ERROR groovy.lang.MissingMethodException: | Error 
> same as groovy (compile error) |
> |4|Class|instanceMethod|error| Function<RetType,Class,Args..>, where method 
> instance method of Class which is declared as ```RetType 
> instanceMethod(Args..) {...}```. In other words it is interpreted as a 
> function which takes LHS Class as the first parameter which additionally 
> inserted to the method.)|
> IMHO, i'd like to propose to change the No 4 pattern semantics of groovy  
> same as Java 8 's. Because:
>  * You can do:
> {code}
> ["a,b,c"].collect ( String.&toUpperCase )
> {code}
> * Can have correspond operator to java8's ::. which is understandablea and 
> needed for Java programmers.



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