Re: lua_Debug in 5.4: add currentpc?

[Dibyendu Majumdar <mobile@...>]

Hi Dan,

On 22 January 2018 at 21:06, Dan Tull <dtull@adobe.com> wrote:
>> On 8 January 2018 at 20:22, Dan Tull <dtull@adobe.com> wrote:
>
>> Are your patches available somewhere such as github?
> Nope, they're internal. Honestly, the only one that was
> significant/interesting was the opcode patching for performant
> breakpoints. The rest are trivial enough that it'd take more work
> (meaning internal hoops to get clearance to release code, etc) to
> share them than they'd take to replicate from a rough description.
>

Okay no problem. I had a look at the performant breakpoint patch. I
have implemented a Lua debugger (using my modified version) for Visual
Studio Code. I found it was difficult to get breakpoints to work
reliably under various conditions, and some debugger features such as
'step over' a statement was particularly troublesome, especially in
the context of co-routines and exceptions. I had not thought about
using a special bytecode as a breakpoint - but I suppose that is
generic way to achieve many of the features needed for a robust
debugger.

>> > That said, we've never bothered (for various reasons) with Lua
>> > versions past 5.1...
>>
>> I am interested to know what the reasons are for staying with 5.1,
>> would be great if you could share.
> Mostly there just hasn't been enough advancement* to merit making
> the move to the new version. I did actually do a bit of work to confirm
> the patches we have did port reasonably easily to Lua 5.2 and 5.3,
> but none of the teams using Lua (mostly Lightroom) had any strong
> reason to make the move, so we haven't bothered.
>
> Also, staying on 5.1 left the door more readily open for teams to
> consider LuaJIT, but nobody made that move either (and probably
> won't at this point).
>

I only started becoming familiar with Lua since 5.3, but by all
accounts 5.1 appears to have been the highpoint - I wonder how much of
that was due to LuaJIT though. Personally I think Lua 5.3 is more
rounded and has a bunch of useful features.

Regards
Dibyendu