[GROOVY-7772] Class.&instanceMethod had better to have same meaning of Class::instanceMethod of Java8

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.4.6
• Fix Version/s: 3.0.0-alpha-1
• Component/s: groovy-runtime
• Assignee: Daniel Sun
• Reporter: UEHARA Junji
• Created: 02/Mar/16 12:56
• Updated: 23/May/19 05:21
• Resolved: 23/May/19 05:21

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 write:

  ["a,b,c"].collect ( String.&toUpperCase )
  

  instaed of

  ["a,b,c"].collect { it.toUpperCase() }
  

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