[Openmcl-devel] ? jfli

[Gary Byers]

I don't know if anyone's using the jfli port or not, but whether
they are or not has nothing to do with whether entry point names
have leading underscores on Darwin.

The old way of looking up the addresses of foreign symbols on Darwin
(which viewed all external symbols as having leading underscores and
required its argument to have such a leading underscore) has been
deprecated (certainly as of Tiger, possibly before - it's been a few
years) in favor of a new (previously deprecated) way which pretends
that Darwin symbols don't have leading underscores (at a lower level,
they still do) and which strips an initial leading underscore from
its argument.  So:

? (foreign-symbol-address "read")
#<A Foreign Pointer #x7FFF81232284>
? (foreign-symbol-address "_read")
#<A Foreign Pointer #x7FFF81232284>

the leading underscore is usually optional, and Apple has cleverly
designed a symbol-lookup mechanism that makes it awkward to refer
to foreign symbols that actually have meaningful leading underscores
in their C-visible names.  (But I digress ...).

You're correct in noting that if the advocated way of resolving
foreign symbol addresses on Darwin still required its argument
to have a leading underscore the jfli example (and lots of other
things, including lots of code in CCL itself) wouldn't work.  Those
things generally do (or at least aren't affected by this ...), and
AFAIK jfli more-or-less does as well.  (The "or less" parts that I'm
aware of have to do with JNI objects not being freed when they should
be, and the general plan is to RTFJNIM to get a clearer idea of when
they should be.)

What's there does seem to work at least well enough to run simple
demos, including the simple SWT demo that's included (assuming that
you can find an SWT library for your platform and can adjust the paths
to it and the JFM that're hardwired into the examples.)  One platform
for which there was not a released SWT library (unless it's been
released very recently) is 64-bit OSX: the OSX version of SWT has been
based on Carbon (and is therefore 32-bit only), though work on a
Cocoa-based version is ongoing.)

Nick Levine made some changes to Rich Hickey's original jfli code
a year or so ago; I wasn't aware of those changes when I did the
CCL port last winter.  Nick's changes include improvements to
pathname handling and ways of abstracting away some Windows/Unix
differences, and it'd be good to merge those changes into the CCL
port when time permits.

There's quite a bit of distance between being able to jump through a
few hoops and get an SWT window to appear (using mostly
platform-neutral code)  and having a rich interface to a mature 
cross-platform GUI toolkit, but getting that window to appear is
a necessary step towards something more interesting.  (Or at least
"maybe interesting.")

On Thu, 11 Jun 2009, james anderson wrote:

> good morning;
>
> is anyone using the ccl jfli port?
> i observe that, for ccl1.3 on os x, the entry point name in the call
> to create a jvn lacks an initial "_" [http://trac.clozure.com/ccl/
> browser/release/1.3/source/examples/jfli/jni.lisp?rev=11690#L1156],
> which makes one wonder.
>
> thanks,
>
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