Re: Status of Strongtalk C++ code: VM stability and progress on a graphical debugger

On May 18, 11:29 pm, Shaping <[email protected]> wrote:
> On May 18, 10:27 am, "Gilad Bracha" <[email protected]> wrote:
>  Does Strongtalk use a
> direct-pointer model?
>

Yes, additionally both compiled and interpreted methods cache
references to classes.

> > A correct implementation of  doesNotUnderstand: is necessary as well.  I
> > understand some people on the list are looking at these issues.
>
> What's wrong with Strongtalk's #doesNotUnderstand:?

It is broken ;)

Basically, method lookups get cached in inline caches. When the class
of the receiver doesn't match the class of the cached method a method
lookup is performed. If a matching method is not found
doesNotUnderstand: gets called, however overriding the implementation
in Object doesn't work quite as expected. Any result returned by the
method is discarded and the lookup just repeats until the stack
overflows.

To fix this, message sends in compiled and interpreted methods need to
allow for a failed lookup followed by an invocation of
doesNotUnderstand: that pops the arguments from the stack and pushes
the result returned by the method.

>
> I poked around in Strongtalk-commit.  Most of the recent submissions
> seem to relate to the gcc build process or to linux.  Is anyone
> developing with the latest version of Visual Studio.  I just asking.
> I don't really want to use it because the VS IDE seems to be broken is
> basic ways, anyway.  What is the most common, least problematic C++
> tool set being used to edit and build Strongtalk C++ code?

Actually, although the commits have been on the Linux branch, the code
on that branch builds under both Linux and Windows. The shared image
used by both has no Linux UI support as yet, but scripted Smalltalk
code can be executed.

Most of the recent work I have been doing has been in Windows using VC+
+ 2008 Express. What problems have you had? I haven't seen any
problems with the environment, only with my code ;)

I'm just about to start looking into some of the issues Gilad is
interested in. In particular, doesNotUnderstand:, automatic garbage
collection and become: Wanna help?

Regards, Steve
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