[GROOVY-7850] Documentation on primitives and wrappers is misleading

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.4.6
• Component/s: Documentation
• Environment: Groovy Version: 2.4.6 JVM: 1.7.0_79 Vendor: Oracle Corporation OS: Mac OS X
• Assignee: Unassigned
• Reporter: Sebb
• Created: 27/May/16 19:54
• Updated: 24/Aug/17 20:09

Description

The doc [1] has the following example:

test1.groovy

int i
m(i)

void m(long l) {     // This is the method that Java would call, since widening has precedence over unboxing.
  println "in m(long)"
}

void m(Integer i) {     // This is the method Groovy actually calls, since all primitive references use their wrapper class.
  println "in m(Integer)"
}

Whilst the comment correctly identifies the method which is called by Groovy, it's somewhat misleading, since the code involves both widening and boxing.

The following code shows why:

test2.groovy

int i
m(i)

void m(int l) { // Groovy calls this method
  println "in m(int)"
}

void m(Integer i) {        
  println "in m(Integer)"
}

In the code sample above, Groovy does not autowrap the primitive int.

See also the following example:

test3.groovy

int i
m(i)

void m(long l) { // called by Groovy        
  println "in m(long)"
}

void m(Long i) {        
  println "in m(Long)"
}

This shows that Groovy widens rather than boxes.

So I think the statement "since all primitive references use their wrapper class." is at best misleading, and may be wrong.

[1] http://groovy-lang.org/differences.html#_primitives_and_wrappers