Re: Desired Lua Features

[Coda Highland <chighland@...>]

On Sun, Jan 28, 2018 at 3:39 PM, Sean Conner <sean@conman.org> wrote:
> It was thus said that the Great Paige DePol once stated:
>>
>> So, if you could add any one feature to Lua right now, what would that
>> feature be and why would you want to see it added? Please note that this
>> discussion is in no way meant to be interpreted as pressuring Team Lua to
>> add any features to Lua, I am genuinely curious what features people want
>> to see added to Lua and why.
>
>   Right now---breakpoints.  Every CPU I've programmed has had such a
> feature.  The x86 has INT3, the MC68000 has TRAPn, MIPS the BREAK, the 6502
> BRK, the 6809 SWI, etc.  I would like to see a Lua VM opcode that does the
> same thing, which could be used to avoid the overhead of hooks (the Lua
> program can run full speed until the breakpoint is hit).
>
>   Some API in the debug module would probably have to be made to support
> this, but it's something I feel would be nice.  Even something as simple as
> tripping on a function call:
>
>         debug.setbreakpoint(target_function,code_to_run)
>
> where code_to_run() can then do the full hooks method if further detail was
> needed.
>
>   -spc

I mean, Javascript has the debugger; statement.

If you want to imitate this behavior, all you need to do is write a
trivial C API function and call it. It checks for a suitable debugger
hook, calls it if present, and returns. This doesn't require any
changes to the VM.

/s/ Adam