[MacRuby-devel] Globbed method arguments (splat) Limit

[Laurent Sansonetti]

Hi,

On Sep 5, 2009, at 3:11 AM, John-Paul Bader wrote:

> Hey guys,
>
>
> a friend of mine implemented a heap in ruby for educational  
> purposes. He did so with several implementations. He had a few  
> benchmarks and I suggested to run them on macruby to see how well it  
> would hold up.
>
> Unfortunately we didn't get really far because apparently there is a  
> problem with globbed/splatted method arguments in macruby which  
> raises an exception if more than 199 arguments are passed.
>
> Can be tested easily with:
>
> def foo(*bar); puts bar.length;end
> 1.upto(1000) {|x| foo(*([0]*x))}
>
> In vm.cpp:2977 #define MAX_DISPATCH_ARGS 200 is defined and a big  
> fat todo is right below it addressing this issue. Now I know its not  
> a super urgent problem because its not what you do in ruby every  
> day. Still its obviously something that has to change.
>
> In line 3003 there is this assert: assert(real_argc + count <  
> MAX_DISPATCH_ARGS);  so it must be important i guess.
>
> So i'm just wondering why it is limited to 200 in the first place  
> and if there is something I can to even though I'm not really a  
> capable (objective) c programmer ?

This limitation is purely temporary and is because of a limitation in  
the dispatcher. This will be addressed for the release.

> After commenting out the code with the globbed arguments the  
> benchmarks on the remaining tests ran a bit slower than on ruby 1.9.1.

Can you share these benchmarks? I would be very interested to see the  
results and also if we can be better.

Laurent