Re: GNAT and JVM

Re: GNAT and JVM

[raould]

There are some things I would kinda like to know re: the recent
announcements. They do a lousy job of explaining WTF their system
actually can do, and how it does it. All buzzwords (JVM! .Net!) and
very insufficient technical details :-(

a) which Java/.Net VMs does it really support? the announcements list
JVM on Windows implying that it doesn't support other JVMs, which is
sorta odd. Would it e.g. be Dalvik-able? Or OpenJDK? Or Mono?

b) is it just the JNI bridge, or does it really optionally compile to
JVM/.Net bytecodes?

c) what are the performance and sizes like?!?!

[d) as an aside, I wonder how likely it is to be able to use GNAT to
develop iPhone ARM apps.]

Anybody have any insights? Thanks!

Re: GNAT and JVM

[Georg Bauhaus]

raould wrote:
> There are some things I would kinda like to know re: the recent
> announcements. They do a lousy job of explaining WTF their system
> actually can do, and how it does it. All buzzwords (JVM! .Net!) and
> very insufficient technical details :-(

Technical detail, tutorial examples, and a supplement to the
User's Guide can be found in the \doc subdirectory after
installation.

> a) which Java/.Net VMs does it really support? 

1.5, 1.6.


> b) is it just the JNI bridge,

No.
JGNAT is a bytecode compiler.
SofCheck's AppletMagic is a bytecode compiler, too.
They both produce .class files.

If you like, you can write Ada packages that mimic Java
class structure. You needn't do that, though. If you do,
then Java programmers can unknowingly use Ada packages
as if they had been written in Java.
The basic idea is to follow certain conventions
when you write the Ada package. (One tagged type,
a controlling parameter of the type, and pragmas for
controlling the mapping to JVM things like constructors).

Re: GNAT and JVM

[Alexey Veselovsky]

> > a) which Java/.Net VMs does it really support?
>
> 1.5, 1.6.

jvm2ada and jvmlist tools does't support java 1.6 :
jvmlist: Bad class file: version 50.0 not supported
jvm2ada: Bad class file: version 50.0 not supported

so, we can't create ada specs for such (modern) java classes ;-(

Re: GNAT and JVM

[Georg Bauhaus]

Alexey Veselovsky wrote:
>>> a) which Java/.Net VMs does it really support?
>> 1.5, 1.6.
> 
> jvm2ada and jvmlist tools does't support java 1.6 :
> jvmlist: Bad class file: version 50.0 not supported
> jvm2ada: Bad class file: version 50.0 not supported
> 
> so, we can't create ada specs for such (modern) java classes ;-(

:-� Last time I checked with SofCheck's java2ada,
version 50.0 files did work...  That's AppletMagic,
not GNAT, but it leaves a choice, so it isn't universally
impossible to create Ada specs from modern class files :-).

Re: GNAT and JVM

[Alexey Veselovsky]

> :-° Last time I checked with SofCheck's java2ada,
> version 50.0 files did work...  That's AppletMagic,
> not GNAT, but it leaves a choice, so it isn't universally
> impossible to create Ada specs from modern class files :-).

Why?

Re: GNAT and JVM

[Georg Bauhaus]

Alexey Veselovsky wrote:
>> :-� Last time I checked with SofCheck's java2ada,
>> version 50.0 files did work...  That's AppletMagic,
>> not GNAT, but it leaves a choice, so it isn't universally
>> impossible to create Ada specs from modern class files :-).
> 
> Why?

Pick the compiler you need and all is well.

O.K., not perfectly well because JGNAT (old),
JGNAT (new), and AppletMagic (any) use almost
the same conventions on the Ada side, but not
exactly the same conventions.

So when you run java2ada (AppletMagic) on a .class file,
not jvm2ada (JGNAT), it produces an Ada package with
some minor differences from what would be produced
by jvm2ada.  Standards are good. ;-)

See
http://en.wikibooks.org/wiki/Ada_Programming/Platform/VM/Java
for some more on this.

(The page is now in need of an update so that it describes
the new JGNAT conventions, too.)

Re: GNAT and JVM

[Gautier]

raould wrote:
> There are some things I would kinda like to know re: the recent
> announcements. They do a lousy job of explaining WTF their system
> actually can do, and how it does it. All buzzwords (JVM! .Net!) and
> very insufficient technical details :-(

Uh, sound familiar. Always wait for service pack 2 ;-).

_________________________________________________________
Gautier's Ada programming -- http://sf.net/users/gdemont/
NB: For a direct answer, e-mail address on the Web site!

Re: GNAT and JVM

[Peter Hermann]

> raould wrote:
> > announcements. They do a lousy job of ...

btw, raould is not authorized to insult ...
unless he generously pays for their first class job