So.. I'm trying to Convert A string into a Roblox instance, like removing the "" from the string
I've tried the loadstring() but its giving me the error loadstring() is not available
Example:
A = "Enum.Keycode.Up" to A = Enum.Keycode.Up
I would appreciate if anyone could help
If your Enum table is global, then you can access it via _G:
Enum = {Keycode={Up="Test"}}
local A = "Enum.Keycode.Up"
local function get_value(a)
local ret = _G
for v in a:gmatch("([^%.]+)") do
if not ret[v] then return nil end
ret = ret[v]
end
return ret
end
print (get_value(A)) -- Test
Related
In the below code, can anyone explain why does t1:print() works but (t1):print fails. I am attempting to make something like (t1 * 3):print() work without using an intermediate variable.
function classTestTable(members)
members = members or {}
local mt = {
__metatable = members;
__index = members;
}
function mt.print(self)
print("something")
end
return mt
end
TestTable = {}
TestTable_mt = ClassTestTable(TestTable)
function TestTable:new()
return setmetatable({targ1 = 1}, TestTable_mt )
end
TestTable t1 = TestTable:new()
t1:print() -- works fine.
(t1):print() -- fails with error "attempt to call a boolean value"
Lua expressions can extend over multiple lines.
print
(3)
Will print 3
So
t1:print()
(t1):print()
actually is equivalent to
t1:print()(t1):print()
or
local a = t1:print()
local b = a(t1)
b:print()
So you're calling the return value of t1:print()
To avoid that follow Egors advice and separate both statements with a semicolon.
t1:print();(t1):print()
I wrote simple class to compress data. Here it is:
LZWCompressor = {}
function LZWCompressor.new()
local self = {}
self.mDictionary = {}
self.mDictionaryLen = 0
-- ...
self.Encode = function(sInput)
self:InitDictionary(true)
local s = ""
local ch = ""
local len = string.len(sInput)
local result = {}
local dic = self.mDictionary
local temp = 0
for i = 1, len do
ch = string.sub(sInput, i, i)
temp = s..ch
if dic[temp] then
s = temp
else
result[#result + 1] = dic[s]
self.mDictionaryLen = self.mDictionaryLen + 1
dic[temp] = self.mDictionaryLen
s = ch
end
end
result[#result + 1] = dic[s]
return result
end
-- ...
return self
end
And i run it by:
local compressor = LZWCompression.new()
local encodedData = compressor:Encode("I like LZW, but it doesnt want to compress this text.")
print("Input length:",string.len(originalString))
print("Output length:",#encodedData)
local decodedString = compressor:Decode(encodedData)
print(decodedString)
print(originalString == decodedString)
But when i finally run it by lua, it shows that interpreter expected string, not Table. That was strange thing, because I pass argument of type string. To test Lua's logs, i wrote at beggining of function:
print(typeof(sInput))
I got output "Table" and lua's error. So how to fix it? Why lua displays that string (That i have passed) is a table? I use Lua 5.3.
Issue is in definition of method Encode(), and most likely Decode() has same problem.
You create Encode() method using dot syntax: self.Encode = function(sInput),
but then you're calling it with colon syntax: compressor:Encode(data)
When you call Encode() with colon syntax, its first implicit argument will be compressor itself (table from your error), not the data.
To fix it, declare Encode() method with colon syntax: function self:Encode(sInput), or add 'self' as first argument explicitly self.Encode = function(self, sInput)
The code you provided should not run at all.
You define function LZWCompressor.new() but call CLZWCompression.new()
Inside Encode you call self:InitDictionary(true) which has not been defined.
Maybe you did not paste all relevant code here.
The reason for the error you get though is that you call compressor:Encode(sInput) which is equivalent to compressor.Encode(self, sInput). (syntactic sugar) As function parameters are not passed by name but by their position sInput inside Encode is now compressor, not your string.
Your first argument (which happens to be self, a table) is then passed to string.len which expects a string.
So you acutally call string.len(compressor) which of course results in an error.
Please make sure you know how to call and define functions and how to use self properly!
I have a lua table which I used to share values between files. But I am getting confused in the following case
utility.lua file
M = {}
M.host_url = '192.168.0.1'
function M.myFunc()
print(M.host_url )
end
return M
in my main.lua
utility = require('utility')
utility.myFunc() -- this gives me 'a nil value' error
I get an error (nil value) for the host_url?
In M.myFunc doing only print action that function nothing will be return.in your utility file returning whole array see he below code that will clear your doudt.
In main.lua
utility = require('util')
value = utility.host_url
print(value)
I have the following problem, somebody can help me?
comp = {}
comp.__index = function(obj,val)
if val == "insert" then
return rawget(obj,"gr")["insert"]
end
return rawget(obj, val)
end
comp.new = function()
local ret = {}
setmetatable(ret, comp)
ret.gr = display.newGroup()
return ret
end
local pru = comp.new()
pru.gr:insert(display.newImage("wakatuBlue.png"))
This line works, but I don't want to access the insert method using the gr property, I want to call the insert method directly and the metatable __index function does the work
pru:insert(display.newImage("wakatuBlue.png"))
This line doesn't work and I get this error: "bad argument #-2 to 'insert' (Proxy expected, got nil)", but this is the way that I'm looking to use
Do you want something like this?
comp = {}
comp.__index = function(obj,val)
if val == "insert" then
return rawget(obj,"gr"):insert(val)
end
return rawget(obj, val)
end
__index works just fine; it's because your last call is interpreted as:
pru.insert(pru, display.newImage("wakatuBlue.png"))
whereas you want/need it to be:
pru.insert(pru.gr, display.newImage("wakatuBlue.png"))
You either need to call it like this or explain what you are trying to do.
What I want to do is this:
object.foo = "bar"
print(object.foo)
where "object" is a userdata.
I've been googling for a while (using the keyword __newindex and lua_rawset) but I can't any examples that do what I want it to do.
I want to do this in with the lua api in c++
Let us write this in Lua code so that we can make quick experiments with the code
function create_object()
-- ## Create new userdatum with a metatable
local obj = newproxy(true)
local store = {}
getmetatable(obj).__index = store
getmetatable(obj).__newindex = store
return obj
end
ud = create_object()
ud.a = 10
print(ud.a)
-- prints '10'
If you work with userdata you probably want to do the above using the C API. However the Lua code should make it clear extactly which steps are necessary. (The newproxy(..) function simply creates a dummy userdata from Lua.)
I gave up trying to do this in C++ so I did it in lua. I loop through all the metatables (_R) and assign the meta methods.
_R.METAVALUES = {}
for key, meta in pairs(_R) do
meta.__oldindex = meta.__oldindex or meta.__index
function meta.__index(self, key)
_R.METAVALUES[tostring(self)] = _R.METAVALUES[tostring(self)] or {}
if _R.METAVALUES[tostring(self)][key] then
return _R.METAVALUES[tostring(self)][key]
end
return meta.__oldindex(self, key)
end
function meta.__newindex(self, key, value)
_R.METAVALUES[tostring(self)] = _R.METAVALUES[tostring(self)] or {}
_R.METAVALUES[tostring(self)][key] = value
end
function meta:__gc()
_R.METAVALUES[tostring(self)] = nil
end
end
The problem with this is what I'm supposed to use for index. tostring(self) only works for those objects with an ID returned to tostring. Not all objects have an ID such as Vec3 and Ang3 and all that.
You could also use a simple table...
config = { tooltype1 = "Tool",
tooltype2 = "HopperBin",
number = 5,
}
print(config.tooltype1) --"Tool"
print(config.tooltype2) --"HopperBin"
print(config.number) --5