Re: Coroutines & C boundaries

[David Given <dg@...>]

On Thursday 16 February 2006 00:53, Mike Pall wrote:
[...]
> Try print(debug.traceback()) immediately before the yield and
> ye shall see.

I'm slightly embarrassed to admit I didn't think about that.

[...]
> No. luaV_execute() is called from two places.
> You want the other one. It's called resume(). :-)

I found that, but I'm never calling it, and it doesn't change nCcalls unless 
cleaning up after an error, so it shouldn't have been relevant.

[...]
> Your problem:
>
> -> lua_resume
> --> resume
> ---> luaV_execute
> ----> luaD_precall
> -----> luaB_pcall or a C function which calls back into Lua <-- !!

The problem was that my coroutine top-level function runs everything inside a 
pcall, so it can trap errors. And pcall, despite being a pure Lua function, 
apparently counts as a C call and you can't yield across it. Ack.

It might be worth emphasising this in the manual; I would never have thought 
of this --- pcall looks like pure Lua, and therefore I assumed that you could 
yield across it.

Now it's all working, and the R is back into my RAD. Thanks for all the help, 
everyone!

-- 
+- David Given --McQ-+ "There is // One art // No more // No less // To
|  dg@cowlark.com    | do // All things // With art // Lessness." --- Piet
| (dg@tao-group.com) | Hein
+- www.cowlark.com --+

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