8 ms·
As it turns out, it’s possible with Lua going back to 5.1 to not allow undeclared global variables: https://www.lua.org/pil/14.2.html https://www.lua.org/pil/1
by strenholme 1y ago
As it turns out, it’s possible with Lua going back to 5.1 to not allow undeclared global variables:
https://www.lua.org/pil/14.2.html https://www.lua.org/pil/14.2.html
That code looks like this in Lua 5.1:
function set(name, val)
rawset(_G, name, val or false)
end
function exists(name)
if rawget(_G, name) then return true end
return false
end
throwError = {__newindex = function(self,name) error("Unknown global " .. name) end,
__index = function(self,name) error("Unknown global " .. name) end
}
setmetatable(_G,throwError)
Then, to use
set("a") -- set"a" also works
a = 1
- ufo 1y agoNaturally, the main catch is that this only detects the violation at run-time. It also won't stop you from accidentally overwriting a global variable that already exists.
- nmz 1y ago> It also won't stop you from accidentally overwriting a global variable that already exists. That's also solvable using metatables.
- Dylan16807 1y agoDo the declarations in 5.5 prevent overwriting? That sounds tricky to define and implement.