[prev in list] [next in list] [prev in thread] [next in thread] 

List:       openjdk-lambda-spec-observers
Subject:    Re: Effective finality requirements for method reference receiver ?
From:       Remi Forax <forax () univ-mlv ! fr>
Date:       2013-02-14 20:16:15
Message-ID: 511D460F.8070900 () univ-mlv ! fr
[Download RAW message or body]

On 02/14/2013 06:12 PM, Dan Smith wrote:
> On Feb 13, 2013, at 9:41 PM, Srikanth S Adayapalam <srikanth_sankaran@in.ibm.com> \
> wrote: 
> > Are there any ?
> > 
> > 0.6.1 - Part C is silent. The words final and capture don't occur there.
> > But SOTL 4th edition talks about the implicit lambda capturing a variable
> > and using that as the receiver. Spec should override all other prose - right ?
> > I also see that the mention of implicit lambda is from a pedagogical pov.
> Here's the relevant spec, from Part E, 15.28.2:
> 
> "If the method reference begins with an ExpressionName or a Primary, the target \
> reference of the invocation is the value of this expression, as determined _at the \
> time_ the method reference was evaluated, and the parameters of the invocation are \
> the parameters of the synthetic method." 
> The intuition is that "Func f = expr::foo;" is translated into something like this:
> 
> final Foo receiver = expr;
> Func f = (x, y) -> receiver.foo(x, y);
> 
> (Hard to actually do such a translation in general, though, since you can't put \
> variable declarations in the middle of an expression.)

FYI, javac has a special node for doing this exact translation 
internally (line 2374 of [1]) but it doesn't use it in that case.

> > BTW, 0.6.1 Part B links to SOTL edition 3 - which is very outdated with respect
> > to the present state of affairs.
> Thanks.  I'll fix that.
> 
> —Dan

Rémi
[1] 
http://hg.openjdk.java.net/lambda/lambda/langtools/file/dae2aede7f35/src/share/classes/com/sun/tools/javac/tree/JCTree.java


> 
> > I see that javac 8b74 compiles this code fine:
> > 
> > // --
> > interface I {
> > void foo();
> > }
> > 
> > public class X {
> > private void foo() {
> > X x = new X();
> > x = new X();
> > I i = x::foo;
> > }
> > }
> > 
> > Thanks in advance for any clarifications.
> > Srikanth.


[prev in list] [next in list] [prev in thread] [next in thread]