Reference implementation

Neal Gafter neal at
Sat Oct 31 23:59:22 PDT 2009

On Sat, Oct 31, 2009 at 8:09 PM, Reinier Zwitserloot <
reinier at> wrote:

> Any given source file will compile the exact same way given a compiler that
> is both java certified and compatible with the version you're using. That's
> true now. That'll be true with a source statement as well.
> So, how is the status quo any different? If I take a certified,
> sun-stamp-of-approval-carrying jikes from the stone age and try to compile
> my shiny new for eaches in it, it'll fail to compile my code.

Well, that conflicts with your goal of having the ability to

1. Instead of being forced to move your entire source base over, you can
just go one file at a time, swapping from source 6 to source 7 as you edit
the files and need to use new features. Your project recompile will just
print whatever incompatibilities arose from changing that one file over;
Fixing these by hand should be a trivial job.

Your certified sun-stamp-of-approval-carrying compiler will accept only a
single source version in a single compilation, corresponding to one
particular Java SE platform specification.  A compiler that does otherwise
would violate the TCK conformance rules.

It appears that we're talking at cross purposes.  Fortunately, the point is
moot, as this feature has not been accepted for Java SE 7, nor specified at
the necessary level of detail, nor implemented in time to be integrated into
the openjdk7 feature-complete milestone.  I'll be happy to discuss it with
you further next time we're in the same area, perhaps over a beer.


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