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One of the new features I found interesting, declarations for global variables, is buried in the reference manual. Here's a link to the section that discusses i
by cturtle 9mo ago
One of the new features I found interesting, declarations for global variables, is buried in the reference manual. Here's a link to the section that discusses it: https://www.lua.org/manual/5.5/manual.html#2.2 https://www.lua.org/manual/5.5/manual.html#2.2
- deleted 9mo ago[deleted]
- rhelz 9mo agoWhy did you find this interesting?
- embedding-shape 9mo agoFor me it's interesting because global variable declarations haven't been needed before, so why now? Also, I'm not sure `global` was reserved before, but now it seems to be.
- TheCycoONE 9mo agolua does not preserve compatibility between minor versions. As such they don't need to reserve words for future use.
- mjmas 9mo agoThe point now is so that if you use a `global` statement in your code, Lua will now error on misspellings of local variables when compiling, rather than defaulting to treat them as globals.
- kevin_thibedeau 9mo agoIt indicates paving the path for local scoping in a future release where Lua 5 code is upgraded with global declarations to keep it working.
- NuclearPM 9mo agoWe have had local scoping for decades.
- HellsMaddy 9mo agoGlobal-by-default scoping was one of Lua's largest mistakes. I wish they'd fix it, but of course it would break backwards compat.
- drcxd 9mo agoStrictly speaking, Lua is not global by default. All free names, that is, all names unqualified with `local`, is actually indexed from a table `_ENV`, which is set to `_G`, the global environment. So, all free names are effectively global by default, but you can change this behavior by put this line at the top of your file `local _G = _G; _ENV = {};`. This way, all free names are indexed from this new table, and all access to the global names must explicitly be accessed through `_G`, which is a local variable now. However, I have never seen such practice. Maybe it is just too complicated to accept that all free names are global variables and you have to explicitly make it local.
- Fwirt 9mo agoThanks to Lua’s great metaprogramming facilities, and the fact that _G is just a table, another workaround is to add a metamethod to _G that throws an error if you try to declare a global. That way you can still declare globals using rawset if you really want them, but it prevents you from declaring them accidentally in a function body.
- kanbankaren 9mo agoyeah. I hate typing `local` for every variable. I would prefer they introduce some syntactic sugar like `let`(to mean local variable) and `const`(to mean local and constant).
- otikik 9mo ago“local” is the same as the “let” that you are describing, isn’t it? Just 2 chars longer.