Thank you for the code. Yamaha sells many routers in Japan and has top share for smaller business. The Yamaha routers has Lua scripting feature to control the configurations such as routing. Your script was quite useful when I implemented a script that hits AWS (Amazon Web Services) APIs on Yamaha routers.

Thanks!
Doi, Koichiro

All that said, the designers of the Language have very clearly stated on many occasions that they’re _not_ trying to please everybody. The goal of the language is not for it to work everywhere in every context. For example, it probably wouldn’t make a great language for numerical simulations, though you could probably use it for that.

If you’re interested in listening to Roberto talk about some of the tradeoffs, he gave a talk at Stanford last year:
video (windows media streaming) and slides.

I really don’t think you can accuse the current version of being thrown together haphazardly, especially given some of it’s technical feats and some of the rather nice and beautiful features it has. Lua 5.x is the first register-based VM to get widely used, and the 5.x design has been a major influence in the last few years’ rounds of JavaScript engine optimizations we’ve seen. That said, I’m damned sure Roberto and others who work on Lua regret some of the early language decisions that they now can’t take back. These, are, I think the sources of some of some of the more minor irritations you’ve expressed in some of the comments above.

I think Adobe also shares some significant blame in how easy it is to work with the Lua that they’ve embedded. I’ve personally have not worked with pure Lua codebases of the Length it sounds like your plugins approach (100kloc+), but having worked with Lua in separate contexts where _I_ was doing the embedding or working with it standalone, I can definitely say I was not hugely impressed with what I saw when I grabbed the “SDK” for Lightroom (after noticing it was extensible through Lua), and I don’t envy having to try and debug code within what looked to be that rather limited and sandboxed environment. One of the things that’s really nice about it is the C API and how easy it is to extend (certainly there are those who complain about the C API being stack based, but whatever, I disagree with this). It’s really dead simple to add functionality to Lua with C code.

Also, here’s SHA224/SHA256 with the availability of the bit functions in Lua 5.2. It looks a fair bit less painful.

If you need a bit more speed on handling sha, you might want to look at the implementation I did based on yours (well, the tests are from your code, the rest is mostly rewritten). It’s roughly about 10 times faster, so it might be of interests for other users as well.

http://cube3d.de/uploads/Main/sha1.txt

Greetings from Germany,
Zet

Look very cool… I don’t need the speed for my uses so don’t need to trade off for the upfront work and for the space your approach uses, but most people will probably find yours to be much preferred. Thanks for sharing! —Jeffrey

I’ve been working on our first commercial Lua plugin (for iPadLightroom synchronization), and after ~15k lines of lua code and far too many hours banging my head against the wall, I can’t agree with you more here. Perl’s tagline is sometimes “Making the easy things easy and hard things possible”; lua’s tagline has to be something along the lines of “Making the easy things hard and the hard things impossible”. It’s atrocious. And using it within the confines of Lightroom is even more so.

I’ve been programming professionally for 18 years- everything from esoteric and academic languages such as ML and Prolog to modern OO languages. Never have I experienced as bad as lua. To say it’s poorly designed is an understatement; you’ve put it in better words than I’ve been able to muster.

What’s more frustrating is Adobe’s incomplete Lightroom exposure of basic lua functions. Want to check an environment variable? Good luck. Want to track background threads? Have fun with that. And on and on. To the person that commented that “it’s not lua’s fault” … that may be, but lua is the language you’re forced to work in if you’re going to integrate with Lightroom.

As an aside, I did perl work for a few years, and your Regex book was my bible – even more than the perl “camel book”. Glad to see you still producing good, quality stuff for the community, even if it’s in lua…

A simple question: what’s the software license with this? Are there any constraints on re-use, redistribution that you’d like respected?

Feel free to use it as you like. —Jeffrey

Once you’ve done this, and looked through the code, and added your next and continue statements if you wish, you might have a different take on it. You might realize that when the Adobe programmers embedded the scripting language they might not have done things as nicely as is possible, or that they didn’t envision someone trying to code an SHA-1 hash on the wrong side of a script engine. Lua has the capability to load external libraries, just code one up using the examples provided in the free docs, load your library and away you go.

I’ve spent 29 years programming in assembly for the 6502 and 80×86 processors, various flavors of BASIC, COBOL, PASCAL, C/C++, Java, Lua, various shell script systems and I’m telling you that Lua is most assuredly not the worst scripting language you could use. A significant number of game projects use it – and everyone who’s ever worked on one knows that performance is something of an issue there. I hardly consider any amount of experience with Lua as an extension to a single application as definitive; there are just too many different ways to handle the embedding and too many ways to hamstring your own performance.

Just work with it outside of your one-application frame of reference and you might actually like it, that’s all I’m trying to say. Your original post is reminiscent of saying that you hate Chinese food because the only restaurant you ever tried it at stank. I’m sure that if I really tried I could do an even worse embedding job than Lightroom’s (theirs is probably pretty good, just not intended for what you did with it). Adobe Lightroom isn’t what I would call “framerate intensive” so I’m sure they weren’t too worried about blazingly fast implementations.

I appreciate your take on things (I have similar experience as you, though no COBOL in my playbook), and I agree that Lua is not the worst scripting language, in absolute terms nor for this specific situation. But that doesn’t mean it’s good in either context, either. Lua was apparently designed by someone without the kind of experience we have… I just can’t imagine a competent engineer designing this language. It has some wonderful attributes and areas of beauty, but it’s not at all designed to be used in the real world. (It *is* used in the real world, and hence my complaints.) —Jeffrey

Thanks.

Regards from Mexico

I seriously doubt that Adobe wrote their image manipulation routines in Lua. If their implementation in LR does not allow 3rd parties to add their own C extension libraries you need to take that up with them. Writing SHA1 or any crypto code in Lua is an inappropriate use of the language.

The ‘continue’ issue is a matter of taste, a correct implementation of tail recursion is more important to me, as is a decent garbage collector and a lack of bloat. I suggest writing some programs in a pure functional language just to get a new perspective, you don’t even get ‘while’

Writing SHA-1 is an inappropriate use of the language? Miss Manners is now reading tech blogs? Indentation is a matter of taste. How one capitalizes identifiers is a matter of taste, but basic language constructs are just that, basic language constructs, and if you don’t have them, you have to go through verbose and awkward hoops whose complexity can increase dramatically in very short order. It’s just another example of how Lua is not designed for creating readable code. (A lot of popular languages have designs that do not encourage or facilitate readable code, but that doesn’t mean it’s not a problem.) What might be a simple, clear, 10-line loop in most any other language can become a deep, cumbersome rats’ nest of conditionals in Lua. There’s a reason we don’t program with nand gates. —Jeffrey

Sorry to hear your troubles with Lua, I think a lot of the troubles you are having with Lua are because the language wasn’t intended to write low-level algorithms like SHA-1. I think that if you had learned the language from a different context (like using it as a language embedded in your program) you would have had a better experience.

Some things that I personally like about Lua are:

* coroutines – Enables my event loop programs to appear linear (similar to lisp’s call/cc).
* Small/Simple – This is important when embedding.
* Garbage Collection – Not reference counting like Perl!
* Well Documented C API – Can’t say that about Perl (`man perlguts`).

I loved your book on regular expressions, perhaps the next edition could even talk a little about lua’s patterns?

BTW, break is mentioned in the manual here:

http://www.lua.org/manual/5.1/manual.html#2.4.5

Issaquah, WA