Attempted to concatenate a nil value? [SOLVED]

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10 years ago

I'm making a ROBLOX implementation of CSS (to be used with GUIs) with a ModuleScript, and I'm getting an error. (These scripts are long but you shouldn't need to read the whole thing)

ModuleScript:

01local module = {}
02 
03local function splitStylesheet(sheet)
04    local split = {}
05 
06    local char = 1
07    local line = 1
08    for i = 1, string.len(sheet) do
09        if string.sub(sheet, char, char) ~= "}" then
10            table.insert(split, line, split[line]..string.sub(sheet, char, char))
11            char = char + 1
12        else
13            line = line + 1
14            char = char + 1
15        end
16    end
17 
18    return split
19end
20 
21local function findSubstyles(dump)
22    print("Splitting dump...")
23 
24    local open = 0
25    local close = 0
26 
27    for brackets in string.gmatch(dump, "{") do
28        open = open + 1
29    end
30 
31    for brackets in string.gmatch(dump, "}") do
32        close = close + 1
33    end
34 
35    if open == close then
36        local substyles = open
37 
38        return substyles
39    elseif open > close then
40        return "open"
41    elseif close > open then
42        return "close"
43    else
44        return "fatal"
45    end
46end
47 
48module.readStylesheet = function(name, dump)
49    print("Reading stylesheet \""..name.."\"")
50 
51    if not name or not dump then
52        error("Missing arg (function readStylesheet)")
53        script:Destroy()
54    end
55 
56    -- find number of substyles
57    local substyles = findSubstyles(dump)
58 
59    if substyles == "open" then
60        error("Assembler detected stray open bracket. Please check stylesheet")
61        script:Destroy()
62    elseif substyles == "close" then
63        error("Assembler detected stray close bracket. Please check stylesheet")
64        script:Destroy()
65    elseif substyles == "fatal" then
66        error("Assembler encountered fatal error. Please check stylesheet")
67        script:Destroy()
68    else
69        print(substyles.." substyles found")
70    end
71 
72    -- split substyles into a table
73    local styletable = splitStylesheet(dump)
74 
75    print(styletable)
76end
77 
78return module
 View all 78 lines...

Script I'm using the Module with (it's in a ScreenGui):

1local css = require(game.Workspace.CSS)
2 
3css.readStylesheet("stylesheet1", "constructor1{background:none;}constructor2{background:none;}")

Output:

53:53.339 - Workspace.CSS:10: attempt to concatenate field '?' (a nil value)
53:53.359 - Stack Begin
53:53.359 - Script 'Workspace.CSS', Line 10 - upvalue splitStylesheet
53:53.360 - Script 'Workspace.CSS', Line 73 - field readStylesheet
53:53.360 - Script 'Players.Player.PlayerGui.PlayerGui.Main', Line 3
53:53.361 - Stack End

Anyone know what the problem is? Thanks to anyone who helps :)

string[line] is nil while you're still inserting the value into the table, so you're going to have to find a way around using string[line]. I would also suggest using tostring() to make sure the entire value you're going to insert is a string. Spongocardo 1991 — 10y

Not sure what you mean by this... DevJackB 55 — 10y

On line 10 when you attempt to call split[line], there is no value in spilt at the spot corresponding with the value for line. You then attempt to concatenate that value (nil) with something else, which is why the error is being thrown. BlackJPI 2658 — 10y

Couldn't have put it any better myself @Masta Spongocardo 1991 — 10y

Attempted to concatenate a nil value? [SOLVED]

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