Lua OOP with metatables, problems loading function from file

Question

I'm trying to store data in a file sufficient to create a metatable 'class' in such a format that it can be loaded in as a function.

The basic idea is here: How do I load data from another lua file?

I have been able to create the file, and load it in successfully. I know all the data is being read because I got syntax errors until the file was correctly formatted. But I cannot access fields in the data.

Edit: thanks to the poster below who pointed out I needed quotes on string values in the written file. Based on that I have it almost working

However, I still have an issue with setting the metatables on the file function after loading. Each plugin object has several banks, and when I load them in, I'm getting an extra bank sub-table. It is either a duplicate of one of the tables (not always the same) and sometimes an malformed table that doesn't implement the tostring method. Here is the code:

local Bank = {}
Bank.__index = Bank

function Bank.new(name,hue,sat,preset)
    local self = setmetatable({}, Bank) 
    self.name = name
    self.hue = hue or 0
    self.sat = sat or 0
    self.params = {}
    self.presets = {preset} or {}
    return self
end

function Bank:addPreset(name)
    table.insert(self.presets,name)
end

function Bank:setParam(control,name)
    self.params[control]=name
end

function Bank:getParam(control)
    return self.params.name
end

function getParamStr(params)
    paramT= {}
    paramStr = 'params = {'
    for control,param in pairs(params) do
        table.insert(paramT,control..' = '..esc(param))
    end
    paramStr = paramStr..table.concat(paramT,',')..'},'
    return paramStr
end

local   Plugin = {}
Plugin.__index = Plugin

function Plugin:__tostring() 
    bankT = {}
    plugStr = 'return {\n'..'name = '..esc(self.name)..', '    
    bankPre = '\n    banks = {\n    '
    for bankName in pairs(self.banks) do 
        table.insert(bankT,tostring(self.banks[bankName]))
    end
    return plugStr..getParamStr(self.params)..bankPre..table.concat(bankT,',\n    ')..'\n    }\n'..'}'  
end
function Bank:__tostring()
    rtnStr = '    '..self.name..' = { '..'name = '..esc(self.name)..', hue = '..self.hue..', sat = '..self.sat..', ' 
    ..getParamStr(self.params)..'\n'
    ..'            presets = {\"'..table.concat (self.presets,'\", \"')..'\" }\n'
    ..'        }'
    return rtnStr
end

function Plugin.new(vstName)
    local self = setmetatable({}, Plugin)
    self.name = vstName
    self.params = {}
    self.banks = {}
    return self
end


function Plugin:getPresetList()
    return table.sort(self.presets)
end

function Plugin:addBank(bankName,hue,sat,preset)
    --just quietly overwrite any existing bank?  for now...
    self.banks[bankName] = Bank.new(bankName,hue,sat,preset)
end

function Plugin:addPresetToBank(bankName,preset)    
    self.banks[bankName]:addPreset(preset)
end

function Plugin:getBank(bank)
    return self.banks[bank]
end

function Plugin:setColor(hue,sat)
    self.hue = hue
    self.sat = sat
end

function Plugin:getColor(level)
    return 'hue: '..self.hue..' and sat: '..self.sat
end

function Plugin:setParam(control,name)
    self.params[control]=name   
end

function Plugin:getParam(control)
    --print(self.params.control)
    return self.params[control]
end

function Bank.init(data)
    local self = setmetatable(data,Bank)
    return self
end

function Plugin.load(filename)
    local f = assert(loadfile('c:\\lua\\'..filename..'.lua'))
    data = f()
    local self = setmetatable(data,Plugin)   
    for bankName,table in pairs(self.banks) do
        self.banks.bankName = Bank.init(table)
    end
    return self
end
function Plugin:save()
    filename = 'c:\\lua\\'..self.name..'.lua'
    local file = io.open(filename,'w')
    file:write(tostring(self))
    file:close() 
end

function Plugin.test(name)
    plug = Plugin.new(name)
    plug:setColor(120,.08)
    plug:setParam('A1','Reverb')
    plug:setParam('A2','Chorus')
    plug:addBank('favorites',120,.05,'Ice Bell')
    plug:addBank('pianos',10,.09,'Black')
    plug:addPresetToBank('pianos','Grandeur')
    plug:addPresetToBank('favorites','OB pad')
    curBank = plug:getBank('favorites')
    curBank:setParam('A5','Wah')
    plug:getBank('pianos'):setParam('A1','Reverb')
    return plug
end

plugName = 'test'
plug = Plugin.test(plugName)
plug:save()
plug2 = Plugin.load(plugName)
print(plug2)
plug2.name = 'test2'
plug2:save()

The data file generated looks like this:

return {
name = "test", params = {A1 = "Reverb",A2 = "Chorus"},
    banks = {
        favorites = { name = "favorites", hue = 120, sat = 0.05, params = {A5 = "Wah"},
            presets = {"Ice Bell", "OB pad" }
        },
        pianos = { name = "pianos", hue = 10, sat = 0.09, params = {A1 = "Reverb"},
            presets = {"Black", "Grandeur" }
        }
    }
}

but after loading I get something like this:

return {
name = "test2", params = {A1 = "Reverb",A2 = "Chorus"},
    banks = {
    table: 00e8eae0,
        favorites = { name = "favorites", hue = 120, sat = 0.05, params = {A5 = "Wah"},
            presets = {"Ice Bell", "OB pad" }
        },
        favorites = { name = "favorites", hue = 120, sat = 0.05, params = {A5 = "Wah"},
            presets = {"Ice Bell", "OB pad" }
        }
    }
}

Not sure where the 'phantom' table is coming from... I also haven't figured out how to avoid duplicating the bank name in the file, but that's not a big deal.

Thanks in advance!!!!

Answer 1

EDIT 1: Making my fields actual strings, and Changing the Plugin init method to this:

function Plugin.init(data)
    self = setmetatable(data,Plugin)
    return self
end

Seems to be working correctly.

EDIT 2:

The problem with strange Bank tables was a syntax error in the Plugin.Load method:

self.banks.bankName = Bank.init(table) --sort of worked??
self.banks[bankName] = Bank.init(table) --good

If anybody can explain why the former delivered unpredictable results, that would be interesting to know. It's not obvious to me. But it works great now.