Code:
local tConst = {
AllowedValueTypes = {"boolean", "number", "string"},
ThrowErrorsByDefault = true, --this can be changed individually for each CONST type created using :SetThrowErrors(boolean);
Types = {},
}
--determines whether or not this CONST type will throw errors
local function GetThrowErrors(sName)
local bRet = false;
if (tConst.Types[sName]) then
bRet = tConst.Types[sName].ThrowErrors;
end
return bRet;
end
--determines whether or not the sumbitted type is an allowed CONST value type
local function IsAllowedValueType(sValueType)
local bRet = false;
for _, sAllowedValueType in pairs(tConst.AllowedValueTypes) do
if (sValueType == sAllowedValueType) then
bRet = true;
break;
end
end
return bRet;
end
--TODO create destroy function
function tConst.Create(sName, sDescription)
--make sure the name input is good
assert(type(sName) == "string" and sName:gsub("s%", "") ~= "",
"Error creating CONST type. Input must be a non-blank string.");
local tReturnTable = {};
--ensure the CONST type doesn't already exist
if (not tConst.Types[sName]) then
if (type(sDescription) ~= "string") then
sDescription = "";
end
--create the CONST shadow table
local tShadow = {
Descriptions = {},
};
--store the CONST type name
tConst.Types[sName] = {
ThrowErrors = tConst.ThrowErrorsByDefault, --set the default error flag for this CONST type
ConstNames = {},
};
--============================================
-- Begin Metamethods
--===========================================
--==========
-- NewIndex
--==========
--this is called whenever a new index is created within the new CONST type table
local function NewIndex(tTable, vKey, vValue)
local sType = type(vValue);
--make sure the CONST has not already been defined
if (tShadow[vKey]) then
if (GetThrowErrors(sName)) then
error('Error creating CONST type. "'..sName..'.'..vKey..
'" has already been defined with value "'..
tostring(tShadow[vKey])..'" and is of type "'..
type(tShadow[vKey])..'".');
end
else
--make sure the CONST is of the correct type
if (IsAllowedValueType(sType)) then
tShadow[vKey] = vValue;
tShadow.Descriptions[vKey] = sDescription;
--add this CONST name to the list of names for this CONST type
tConst.Types[sName].ConstNames[#tConst.Types[sName].ConstNames + 1] = vKey;
else
--throw an error (if errors are on)
if (GetThrowErrors(sName)) then
error('Error creating CONST type. A CONST type "'..sName..
'" value may be of type "boolean", "number" or "string" only. Input was of type "'..
sType..'".');
end
end
end
end
--=========
-- GetAll
--=========
--__call
local function GetAll()
local tRet = {};
for k, v in pairs(tShadow) do
local sVType = type(v);
if (type(k) == "string" and IsAllowedValueType(sVType)) then
tRet[k] = v;
end
end
return tRet;
end
--============================================
-- End Metamethods
--
-- Begin CONST type exposed functions
--============================================
--this is the table whose metatable is set and is used to set functions
local tConstType = {};
--================
-- GetDescription
--================
function tConstType.GetDescription(sKey)
assert(tShadow[sKey], "Error getting CONST description. CONST does not exist.");
return tShadow.Descriptions[sKey];
end
--================
-- SetThrowErrors
--================
function tConstType.SetThrowErrors(bValue)
local sType = type(bValue);
local bFlag = bValue;
if (sType ~= "boolean") then
bFlag = false;
end
tConst.Types[sName].ThrowErrors = bFlag;
end
--================
-- IsConstOfType
--[[================
Note: this method will return true if the
input value matches *any* value in the table.
]]
function tConstType.IsMyConst(vValue)
local bRet = false;
local sType = type(vValue);
if (sType ~= "nil") then
for sCONST, vConstValue in pairs(tConstType()) do
if vValue == vConstValue then
bRet = true;
break;
end
end
end
return bRet
end
--================
-- SetDescription
--================
function tConstType.SetDescription(sKey, sDescription)
assert(tShadow[sKey], "Error setting CONST description. CONST does not exist.");
assert(type(sDescription) == "string", "Error setting CONST description. Description must be a string.");
tShadow.Descriptions[sKey] = sDescription;
end
--adjust the metatable of the new tConstType and return that value
tReturnTable = setmetatable(tConstType, {
__call = GetAll,
__len = function() return #tConst.Types[sName].ConstNames end, --does not work with Lua Version <= 5.1
__index = tShadow, --the shadow reference
__newindex = NewIndex,
__type = sName,
});
else
tReturnTable = _G[sName];
if (GetThrowErrors(sName)) then
error("Error creating CONST type. CONST type already exists.");
end
end
return tReturnTable;
end
CONST = tConst.Create;
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