World: r4wp

Another note: messing up with the stack (using push/pop) in a user-function 
is fine as long as you returned the stack clean before calling a 
function that could generate an exception. Failure to do so will 
result in a crash. It might be possible to make stack-unwinding for 
exception resistant to such cases, I will investigate that.

Exception handling code pushed. Have fun! ;)

(only IA-32 for now, will add ARM support in the next days)

That sounds great Doc. I collected your comments into a file in %Red/.

Hmm, shouldn't bar print KO in the second example, from your description?

Nope, see first example. This might be a bit non/counter-intuitive, 
I will see if I can improve that.

Ah, I get it now. Yes, that wasn't obvious at first.

I won't be online tomorrow most of the day, will look into that and 
will upgrade the documentation tomorrow night.

So you don't check system/thrown in the func with [catch], correct?

But in the func that *called* the func with [catch].

Right.

I might adjust that tomorrow if possible to make it more intuitive.

Absolutely fabulous Nenad!!!

Good progress. Nice of you to sum it up Gregg, makes the comments 
a whole lot more readable. Filename is a bit awkward though: "esceptions"

Fixed. Thanks Arnold.

I had a Spanish accent last night.

Gregg, I've reconsidered the behavior of the [catch] function attribut, 
if I change it, some use cases become even less intuitive. For example, 
the single function use case (my first example above) performs quite 
intuitively. I think the  vague non-intuitive feeling at the beginning 
comes from our habits with CATCH native in Rebol, after using Red/System's 
way a bit, that feeling just faded away. Anyway, if you have suggestions 
for improvements, it's the right time.

Doc, any idea how I can convert a string! passed into a routine! 
to UTF-8, or access a cached UTF-8 value?

Kaj, can you use string/mold inside the routine to create a c-string! 
?

The answer is not you can't as mold doesnt output a UTF-8 string.

Kaj: cached UTF-8 string is available using str/cache if str is a 
red-string! value.

Only small strings (< 64 bytes) are cached.

We haven't yet implemented UTF-8 encoding functions in the standard 
library. It will be done during the I/O implementation (unless you 
have a strong need for it, then I'll have a look at it).

After trying to use the new exception handling in the interpreter 
to implement EXIT/RETURN, I realized that the current behavior of 
the [catch] attribut is not suitable in a intensively recursive environment. 
So I had to change the moment the exceptions are caught to an earlier 
time. Now, it works like this:

	foo: does [
		print "3"
		throw 100
		print "KO"
	]

	bar: func [[catch]][
		print "2"
		foo
		print "4"
	]

	print "1"
	bar

will output: 1234


So, now the [catch] attribut resumes the execution at the current 
level, instead of the parent caller level like before.

The catch flags position on stack has been changed to a safer place, 
so it's now resistant to a "dirty" stack left by user code (unbalanced 
PUSH/POP actions at the exception raising point).

A [catch] flag will have no effect on exceptions launched from the 
same level (enables re-throwing exceptions).

EXIT and RETURN have been implemented for the interpreter too now. 
All related tests are now passing. An important fact to note, which 
differs from the Rebol way:


EXIT and RETURN are dialect keywords in Red, not native functions. 
Both the compiler and the interpreter are processing them as part 
of function's body dialect.

@Ladislav, I know you don't care much about Red, but you might be 
pleased to see that some of your old propositions for Rebol found 
their way into Red. ;-)

Can't speak for Ladislav, but maybe he is mostly busy with other 
stuff, so he'll wait, how Red turns out in the end :-)

So, now as exceptions are working, my typical - what's next? :-) 
Dyn-lib emmiter? Contexts? IO? :-)

Shared lib generation for Mac OS X and Linux.

Does that include ARM?

Not sure if you mean for exceptions or shared libs, so:
- Exceptions: I will push the upgraded ARM version in a few hours
- Shared lib: yes, we will support it on ARM too

I meant shared libs

...you might be pleased to see that some of your old propositions 
for Rebol found their way into Red
 - yes, that is great!

EXIT from a func exits the console. Is that intended?

N ope.

The console needs a [catch] somewhere to avoid such exceptions reach 
global code and exit from console.

Ahhh, makes sense.

Should I log it as ain issue?

No need, I will process tonight as I need to do a bit more work on 
exceptions (like documenting them).

OK.

Gregg, can't reproduce your console issue, here's the test code I'm 
using:

red>> foo: func [][print "1" exit print "2"]
== func [][print "1" exit print "2"]
red>> foo
1
red>>

Hmmm, neither can I now. Thanks for checking.

Uncaught exceptions in Red/System (THROW) currently won't stop execution 
and report an error when reaching global code, but would just resume 
from there. I wonder if this is really the best behavior for the 
user, or if an error shouldn't be forced... OTOH, there is no way 
currently to catch an exception at global code level, so if the behavior 
is changed to an error, it might result in users making wrapper functions 
to avoid the error and resume at global level ...

I guess I will probably keep it as is for now, we'll see when we'll 
have some way to catch exceptions manually at global level.

You could still check system/thrown though, correct? And if you wanted 
to catch them, you could just have a MAIN func?

Correct. Yes, it is possible to wrap all your global code in a MAIN 
func.

That should be comfrotable for C programmers, yes?

Even if not required.