[Opensim-users] use of C# in scripts

[Serendipity Seraph]

As a software engineer the things that deeply bug me about LSL include:

1) no real way to get reuse vs copy and paste where needed.  Major blow to
possible efficiency gains of not having multiple copies and to
maintainability.  No import/include or library concept or support.

2) almost no real data structures  and no way to roll your own.  Yeah you
can do 1970s era hacks sort of.


On Tue, Feb 26, 2019 at 12:24 PM Serendipity Seraph <seren.seraph at gmail.com>
wrote:

> AFAIK the JVM garbage collection is as efficient as Lisp garbage
> collection.  In fact some of the same people worked on both.  And much of
> this tech was used in the C# underlying CLR as well.  So I doubt very much
> that GC is a critical issue, especially in small opensim scripts.
>
> On Sun, Feb 24, 2019 at 4:00 AM Ethan Gardener <eekee57 at fastmail.fm>
> wrote:
>
>> On Sat, Feb 23, 2019, at 8:11 PM, Dr Ramesh Ramloll wrote:
>> > I think the assumption that C# should work only in closed secure
>> > environments kind of narrows down the application space by quite a bit,
>> > like 90% or more.
>>
>> Yeah.  It narrows it down to about the same space as custom modules, so
>> why not write them instead?
>>
>> This is one area where I wish OpenSim had branched out a bit; adding
>> other languages, but I guess there was no-one to work on it.  I wasn't up
>> to the task myself, as much as I wished I was.  Making a safe interpreter
>> is non-trivial anyway.  Lately, I've been looking at one of the problems,
>> avoiding memory leaks (which could lead to a denial of service attack or
>> possibly an overflow exploit).  This alone is not at all easy to solve
>> efficiently.  It would be better if modern computers descended from the
>> Lisp Machines of the 1980s, they had hardware support for automatic garbage
>> collection, but instead we have virtual memory schemes which make it hard
>> for garbage collectors to work efficiently.  (I don't think anyone really
>> wants to pay for the extra bits this needs.  The cost of memory was a huge
>> limiting factor through the '80s and much of the '90s, and remains a little
>> bit of a problem today.)
>>
>> I can solve my problems with a relatively inefficient design, but that
>> would be ridiculous in an environment where a single simulator may have to
>> run thousands of scripts.  I could hypothetically write a full-blown
>> garbage collector, but it's not worth it because such garbage collectors
>> are notoriously prone to bugs, and *still* have efficiency problems.
>> Garbage collectors are one of those things which exponentially approach
>> infinite complexity as they approach correctness and efficiency.
>>
>> Is a simple, efficient design possible?  Yes... if you limit the possible
>> data structures.  ;)  Particularly, never allow complex data types to
>> contain references to other complex data types, that prevents reference
>> loops which are *the* problem requiring complex garbage collectors.  I
>> haven't chosen this for my comparatively inefficient design, I've chosen to
>> make all data structures immutable; if you want to change something, you
>> have to copy the structure.  That way, it's impossible for a structure to
>> contain a reference to itself because the structure becomes immutable
>> before the public reference to it exists.  This very much goes against the
>> grain, I've been exploring every other way of doing it, but I figure if
>> it's good enough for high finance it ought to be good enough for me.  I
>> wonder if it might actually be good enough for OpenSim.  Maybe I'll run
>> some experiments comparing scale, but my system probably won't be ready for
>> that for a long time yet.  My health isn't
>>  helping me get on with it.
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>