Added to common and added more comments to groups

expcore/common.lua

@@ -13,6 +13,44 @@ function Public.type_check(value,test_type)
     return test_type and value and type(value) == test_type or not test_type and not value or false
 end
 
+--- Raises an error if invalid type is given
+-- @tparam value any the value that you want to test the type of
+-- @tparam test_type string the type that the value should be
+-- @tparam error_message string the error message that is returned
+-- @tparam level number the level to call the error on (level = 1 means the caller)
+-- @treturn boolean true if no error was called
+function Public.type_check_error(value,test_type,error_message,level)
+    level = level and level+1 or 2
+    return Public.test_type(value,test_type) or error(error_message,level)
+end
+
+--- Raises an error with type error with a consistent error message
+-- @tparam value any the value that you want to test the type of
+-- @tparam test_type string the type that the value should be
+-- @tparam param_name string the name of the param
+-- @tparam param_number number the number param it is
+-- @treturn boolean true if no error was raised
+function Public.param_check(value,test_type,param_name,param_number)
+    if not Public.test_type(value,test_type) then
+        local function_name = debug.getinfo(2,'n').name or '<anon>'
+        local error_message = string.format('Invalid param #%2d given to %s; %s is not of type %s',param_number,function_name,param_name,test_type)
+        return error(error_message,3)
+    end
+    return true
+end
+
+--- Extracts certain keys from a table
+-- @tparam tbl table the table which contains the keys
+-- @tparam ... string the names of the keys you want extracted
+-- @return the keys in the order given
+function Public.extract_keys(tbl,...)
+    local values = {}
+    for _,key in pairs({...}) do
+        table.insert(values,tbl[key])
+    end
+    return unpack(values)
+end
+
 --- Will return a value of any type to the player/server console, allows colour for in-game players
 -- @usage player_return('Hello, World!') -- returns 'Hello, World!' to game.player or server console
 -- @usage player_return('Hello, World!','green') -- returns 'Hello, World!' to game.player with colour green or server console
@@ -54,4 +92,25 @@ function Public.player_return(value,colour,player)
     else rcon.print(returnAsString) end
 end
 
+--- Calls a require that will not error if the file is not found
+-- @tparam path string the path that you want to require
+-- @return the returns from that file or nil, error if not loaded
+function Public.opt_require(path)
+    local success, rtn = pcall(require,path)
+    if success then return rtn
+    else return nil,rtn end
+end
+
+--- Calls a require and returns only the keys given, file must return a table
+-- @tparam path string the path that you want to require
+-- @tparam ... string the name of the keys that you want returned
+-- @return the keys in the order given
+function Public.ext_require(path,...)
+    local rtn = require(path)
+    if type(rtn) ~= 'table' then
+        error('File did not return a table, can not extract keys.',2)
+    end
+    return Public.extract_keys(rtn,...)
+end
+
 return Public