Module:CallAssert
MyWikiBiz, Author Your Legacy — Wednesday December 25, 2024
Jump to navigationJump to searchTemplate:Module rating Template:Used in system This metamodule provides function callAssert, which simplifies error checking by throwing an error if a given function returns nil or false. This is similar to the built-in function assert, but unlike it, callAssert itself calls the function, whose return value is to be checked. This allows it to include the function name and argument values in the error message.
Usage
local callAssert = require('Module:CallAssert') local result1, result2, etc = callAssert(func, Template:'funcNameTemplate:', ...)
callAssert
calls func(...)
and checks if the first returned value evaluates to true. If it does, then it returns all the returned values. If not, it throws an error with a message in the form Template:'funcName(argument_values) failed'
.
local function pack(...) return {...}, select('#', ...) end local function mapArray(func, array, count) local result = {} for i = 1, count or #array do result[i] = func(array[i]) end return result end local function quote(value) if type(value) == 'string' then return (string.gsub(string.format('%q', value), '\\\n', '\\n')) -- Outer parentheses remove second value returned by gsub end local str = tostring(value) if type(value) == 'table' and str ~= 'table' then return '{' .. str .. '}' end return str end local function callAssert(func, funcName, ...) local result, resultCount = pack(func(...)) if not result[1] then local args, argsCount = pack(...) args = mapArray(quote, args, argsCount) local message = mw.ustring.format( '%s(%s) failed', funcName, table.concat(args, ', ') ) error(message, 2) end return unpack(result, 1, resultCount) end return callAssert