Wireshark mailing list archives
Re: Lua 5.3
From: João Valverde <joao.valverde () tecnico ulisboa pt>
Date: Fri, 19 Aug 2016 16:05:34 +0100
On 08/19/2016 03:56 PM, João Valverde wrote:
On 08/19/2016 02:54 PM, Peter Wu wrote:On Mon, Aug 08, 2016 at 09:17:35PM +0100, João Valverde wrote:On 08/08/2016 05:58 PM, Pascal Quantin wrote:Hi João, 2016-08-08 18:52 GMT+02:00 João Valverde <joao.valverde () tecnico ulisboa pt <mailto:joao.valverde () tecnico ulisboa pt>>: Is moving to Lua 5.3 something we should look into? The 64 bit integer support seems really promising. Hariel explained us that Lua 5.3 was a completely different language (a bit like what you have between Python 2.X and 3.X). You can find much more info (from people knowing what they are taling about - so not me ;)) in bug 10881. Pascal.Thanks for that Pascal. The only sane way to approach the issue IMHO is to accept that this may and probably will break backward compatibility (not even think about supporting 5.1 or 5.2) and just consider whether that break is justified (hint: it is).Why is it justified to break backwards compatibility and move from 5.2 to 5.3 without the ability to chose for 5.2? What is the killer feature of 5.3 that makes it totally worth to possibly break older dissectors? The disadvantage of C plugins is that it had to be recompiled for newer versions. With a move from 5.2 to 5.3 and also removing GRegex and bitop you make it quite likely to break Lua dissectors in some way. I have once written a Lua library in C, interfacing with Libgcrypt for which I studied the Lua manual. The API changes with 5.3 were not that significant if I remember correctly (though you have to be careful with providing a compatibility layer), but the ABI is certainly not compatible. In the recent proposed patches, you seem to have no issues with breaking backwards compatibility. Have you developed Lua dissectors before? Breaking things for the sake of "shiny, new, future" is not an acceptable motivation, there must be something more appealing to justify such breakage. Having 64-bit integer support, but taking away the bitop library is a net loss without even considering the other factors.Doesn't Lua 5.3 provide native bit operators? If so there is not net loss of functionality. That was my reasoning at least. The language incompatibilities between 5.2 and 5.3 are minor. The wireshark API is exactly the same. LPeg is more powerful and Lua-thonic than lrexlib, but there is a learning curve for that, no doubt. For anyone relying on lrexlib, it's a significant break. We can keep lrexlib, that's not a problem and it is orthogonal to the other changes. As far as killer features go, besides the obvious, how about better UTF-8 support? I don't have time for a more detailed answer right now but I'd like to say I think this change is entirely justified but I also completely understand disagreeing with that opinion.
I'm referring to the upgrade to Lua 5.3 here, i.e, breaking backward compatibility, same as any other Lua script moving from 5.1/5.2 to 5.3.
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Current thread:
- Lua 5.3 João Valverde (Aug 08)
- Re: Lua 5.3 Pascal Quantin (Aug 08)
- Re: Lua 5.3 João Valverde (Aug 08)
- Re: Lua 5.3 João Valverde (Aug 19)
- Re: Lua 5.3 Peter Wu (Aug 19)
- Re: Lua 5.3 João Valverde (Aug 19)
- Re: Lua 5.3 João Valverde (Aug 19)
- Re: Lua 5.3 Pascal Quantin (Aug 19)
- Re: Lua 5.3 João Valverde (Aug 19)
- Re: Lua 5.3 João Valverde (Aug 19)
- Re: Lua 5.3 Peter Wu (Aug 20)
- Re: Lua 5.3 João Valverde (Aug 20)
- Re: Lua 5.3 João Valverde (Aug 20)
- Re: Lua 5.3 João Valverde (Aug 20)
- Re: Lua 5.3 Jeff Morriss (Aug 22)
- Re: Lua 5.3 João Valverde (Aug 22)
- Re: Lua 5.3 João Valverde (Aug 08)
- Re: Lua 5.3 Pascal Quantin (Aug 08)
- Re: Lua 5.3 João Valverde (Aug 20)