Module:Arguments: Difference between revisions
don't use "if frame == mw.getCurrentFrame()" |
memoize nils, add type checks for frame and options, use string library functions instead of mw.text.trim and mw.ustring.find, define four different tidyVal functions to avoid checking options every time |
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Line 1: | Line 1: | ||
-- This module provides easy processing of arguments passed to Scribunto from #invoke. |
-- This module provides easy processing of arguments passed to Scribunto from #invoke. |
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-- It is intended for use by other Lua modules, and should not be called from #invoke directly. |
-- It is intended for use by other Lua modules, and should not be called from #invoke directly. |
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local libraryUtil = require('libraryUtil') |
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local checkType = libraryUtil.checkType |
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local arguments = {} |
local arguments = {} |
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local nilArg = {} -- Used for memoizing nil arguments in metaArgs. |
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-- Generate four different tidyVal functions, so that we don't have to check the options every time we call it. |
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local function tidyValDefault(key, val) |
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if type(val) == 'string' then |
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val = val:match('^%s*(.-)%s*$') |
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if val == '' then |
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return nil |
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else |
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return val |
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end |
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else |
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return val |
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end |
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end |
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local function tidyValTrimOnly(key, val) |
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if type(val) == 'string' then |
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return val:match('^%s*(.-)%s*$') |
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else |
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return val |
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end |
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end |
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local function tidyValRemoveBlanksOnly(key, val) |
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if type(val) == 'string' then |
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if val:find('%S') then |
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return val |
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else |
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return nil |
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end |
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else |
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return val |
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end |
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end |
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local function tidyValNoChange(key, val) |
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return val |
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end |
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function arguments.getArgs(frame, options) |
function arguments.getArgs(frame, options) |
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checkType('getArgs', 1, frame, 'table', true) |
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options = type(options) == 'table' and options or {} |
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checkType('getArgs', 2, options, 'table', true) |
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frame = frame or {} |
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options = options or {} |
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-- Get the arguments from the frame object if available. If the frame object is not available, we are being called |
-- Get the arguments from the frame object if available. If the frame object is not available, we are being called |
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-- from another Lua module or from the debug console, so put the args in a special table so we can differentiate them. |
-- from another Lua module or from the debug console, so put the args in a special table so we can differentiate them. |
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local fargs, pargs, luaArgs |
local fargs, pargs, luaArgs |
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if |
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then |
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if not options.parentOnly then |
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fargs = frame.args |
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fargs = frame.args |
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end |
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if not options.frameOnly then |
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pargs = frame:getParent().args |
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end |
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if options.parentFirst then |
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fargs, pargs = pargs, fargs |
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end |
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else |
else |
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luaArgs = |
luaArgs = frame |
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end |
end |
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Line 22: | Line 76: | ||
setmetatable(args, metatable) |
setmetatable(args, metatable) |
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-- Generate the tidyVal function. If it has been specified by the user, we use that; if not, we choose one of four functions |
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local function tidyVal(key, val) |
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-- depending on the options chosen. This is so that we don't have to call the options table every time the function is called. |
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-- Processes a value according to the options given to getArguments. Can trim whitespace and remove blanks. |
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local tidyVal = options.valueFunc |
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-- Keys are not used here, but they can be used by user-generated functions, so defining it here to avoid breakage. |
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if tidyVal then |
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if type(tidyVal) ~= 'function' then |
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error("bad value assigned to option 'valueFunc' (function expected, got " .. type(tidyVal) .. ')', 2) |
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val = mw.text.trim(val) |
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end |
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elseif options.trim ~= false then |
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if options.removeBlanks ~= false then |
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return val |
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tidyVal = tidyValDefault |
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end |
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else |
else |
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tidyVal = tidyValTrimOnly |
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return val |
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end |
end |
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else |
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end |
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if options.removeBlanks ~= false then |
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tidyVal = tidyValRemoveBlanksOnly |
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-- Use a user-generated function to tidy the values if specified. |
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local valueFunc = options.valueFunc |
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if valueFunc then |
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local valueFuncType = type(valueFunc) |
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if valueFuncType == 'function' then |
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tidyVal = valueFunc |
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else |
else |
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tidyVal = tidyValNoChange |
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error('type error in option "valueFunc": expected function, got ' .. valueFuncType, 2) |
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end |
end |
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end |
end |
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Line 51: | Line 100: | ||
-- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator. |
-- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator. |
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-- If a value is already present it is not overwritten; tables listed earlier have precendence. |
-- If a value is already present it is not overwritten; tables listed earlier have precendence. |
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-- We are also memoizing nil values, but those values can be overwritten. |
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for _, t in ipairs(tables) do |
for _, t in ipairs(tables) do |
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for key, val in iterator(t) do |
for key, val in iterator(t) do |
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local metaArgsVal = metaArgs[key] |
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if metaArgsVal == nil or metaArgsVal == nilArg then |
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metaArgs[key] = tidyVal(key, val) |
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local tidiedVal = tidyVal(key, val) |
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if tidiedVal == nil then |
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metaArgs[key] = nilArg |
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else |
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metaArgs[key] = tidiedVal |
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end |
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end |
end |
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end |
end |
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Line 61: | Line 117: | ||
-- Set the order of precedence of the argument tables. If the variables are nil, nothing will be added to the table, |
-- Set the order of precedence of the argument tables. If the variables are nil, nothing will be added to the table, |
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-- which is how we avoid clashes between the frame/parent args and the Lua args. |
-- which is how we avoid clashes between the frame/parent args and the Lua args. |
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local argTables = {} |
local argTables = {fargs} |
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argTables[#argTables + 1] = pargs |
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if options.frameOnly then |
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argTables[#argTables + 1] = luaArgs |
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table.insert(argTables, fargs) |
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elseif options.parentOnly then |
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table.insert(argTables, pargs) |
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elseif options.parentFirst then |
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table.insert(argTables, pargs) |
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table.insert(argTables, fargs) |
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else |
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table.insert(argTables, fargs) |
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table.insert(argTables, pargs) |
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end |
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table.insert(argTables, luaArgs) |
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--[[ |
--[[ |
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-- Define metatable behaviour. Arguments are |
-- Define metatable behaviour. Arguments are memoized in the metaArgs table, and are only fetched from the |
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-- argument tables once. |
-- argument tables once. Nil arguments are also memoized using the nilArg variable in order to increase |
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-- performance. Also, we keep a record in the metatable of when pairs and ipairs have been called, so we |
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-- so we do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs |
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-- |
-- do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs and |
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-- pargs if pairs has already been run, as all the arguments will already have been copied over. |
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--]] |
--]] |
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metatable.__index = function (t, key) |
metatable.__index = function (t, key) |
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local val = metaArgs[key] |
local val = metaArgs[key] |
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if val ~= nil then |
if val ~= nil then |
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if val == nilArg then |
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return nil |
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else |
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else |
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for i, argTable in ipairs(argTables) do |
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return val |
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local argTableVal = tidyVal(key, argTable[key]) |
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if argTableVal ~= nil then |
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metaArgs[key] = argTableVal |
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return argTableVal |
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end |
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end |
end |
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end |
end |
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for _, argTable in ipairs(argTables) do |
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local argTableVal = tidyVal(key, argTable[key]) |
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if argTableVal == nil then |
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metaArgs[key] = nilArg |
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else |
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metaArgs[key] = argTableVal |
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return argTableVal |
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end |
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end |
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return nil |
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end |
end |
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metatable.__newindex = function (t, key, val) |
metatable.__newindex = function (t, key, val) |
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if |
if options.readOnly then |
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error('could not write to argument table key "' .. tostring(key) .. '"; the table is read-only', 2) |
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elseif options.noOverwrite and args[key] ~= nil then |
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error('could not write to argument table key "' .. tostring(key) .. '"; overwriting existing arguments is not permitted', 2) |
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elseif val == nil then |
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metaArgs[key] = nilArg -- Memoize nils. |
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else |
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metaArgs[key] = val |
metaArgs[key] = val |
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end |
end |
Revision as of 13:06, December 11, 2013
This module provides easy processing of arguments passed from #invoke. It is a meta-module, meant for use by other modules, and should not be called from #invoke directly. Its features include:
- Easy trimming of arguments and removal of blank arguments.
- Arguments can be passed by both the current frame and by the parent frame at the same time. (More details below.)
- Arguments can be passed in directly from another Lua module or from the debug console.
- Most features can be customized.
Basic use
First, you need to load the module. It contains one function, named getArgs
.
local getArgs = require('Module:Arguments').getArgs
In the most basic scenario, you can use getArgs inside your main function. The variable args
is a table containing the arguments from #invoke. (See below for details.)
local getArgs = require('Module:Arguments').getArgs
local p = {}
function p.main(frame)
local args = getArgs(frame)
-- Main module code goes here.
end
return p
However, the recommended practice is to use a function just for processing arguments from #invoke. This means that if someone calls your module from another Lua module you don't have to have a frame object available, which improves performance.
local getArgs = require('Module:Arguments').getArgs
local p = {}
function p.main(frame)
local args = getArgs(frame)
return p._main(args)
end
function p._main(args)
-- Main module code goes here.
end
return p
If you want multiple functions to use the arguments, and you also want them to be accessible from #invoke, you can use a wrapper function.
local getArgs = require('Module:Arguments').getArgs
local p = {}
local function makeInvokeFunc(funcName)
return function (frame)
local args = getArgs(frame)
return p[funcName](args)
end
end
p.func1 = makeInvokeFunc('_func1')
function p._func1(args)
-- Code for the first function goes here.
end
p.func2 = makeInvokeFunc('_func2')
function p._func2(args)
-- Code for the second function goes here.
end
return p
Options
The following options are available. They are explained in the sections below.
local args = getArgs(frame, {
trim = false,
removeBlanks = false,
valueFunc = function (key, value)
-- Code for processing one argument
end,
frameOnly = true,
parentOnly = true,
parentFirst = true,
wrappers = {
'Template:A wrapper template',
'Template:Another wrapper template'
},
readOnly = true,
noOverwrite = true
})
Trimming and removing blanks
Blank arguments often trip up coders new to converting MediaWiki templates to Lua. In template syntax, blank strings and strings consisting only of whitespace are considered false. However, in Lua, blank strings and strings consisting of whitespace are considered true. This means that if you don't pay attention to such arguments when you write your Lua modules, you might treat something as true that should actually be treated as false. To avoid this, by default this module removes all blank arguments.
Similarly, whitespace can cause problems when dealing with positional arguments. Although whitespace is trimmed for named arguments coming from #invoke, it is preserved for positional arguments. Most of the time this additional whitespace is not desired, so this module trims it off by default.
However, sometimes you want to use blank arguments as input, and sometimes you want to keep additional whitespace. This can be necessary to convert some templates exactly as they were written. If you want to do this, you can set the trim
and removeBlanks
arguments to false
.
local args = getArgs(frame, {
trim = false,
removeBlanks = false
})
Custom formatting of arguments
Sometimes you want to remove some blank arguments but not others, or perhaps you might want to put all of the positional arguments in lower case. To do things like this you can use the valueFunc
option. The input to this option must be a function that takes two parameters, key
and value
, and returns a single value. This value is what you will get when you access the field key
in the args
table.
Example 1: this function preserves whitespace for the first positional argument, but trims all other arguments and removes all other blank arguments.
local args = getArgs(frame, {
valueFunc = function (key, value)
if key == 1 then
return value
elseif value then
value = mw.text.trim(value)
if value ~= '' then
return value
end
end
return nil
end
})
Example 2: this function removes blank arguments and converts all arguments to lower case, but doesn't trim whitespace from positional parameters.
local args = getArgs(frame, {
valueFunc = function (key, value)
if not value then
return nil
end
value = mw.ustring.lower(value)
if mw.ustring.find(value, '%S') then
return value
end
return nil
end
})
Note: the above functions will fail if passed input that is not of type string
or nil
. This might be the case if you use the getArgs
function in the main function of your module, and that function is called by another Lua module. In this case, you will need to check the type of your input. This is not a problem if you are using a function specially for arguments from #invoke (i.e. you have p.main
and p._main
functions, or something similar).
Template:Cot Example 1:
local args = getArgs(frame, {
valueFunc = function (key, value)
if key == 1 then
return value
elseif type(value) == 'string' then
value = mw.text.trim(value)
if value ~= '' then
return value
else
return nil
end
else
return value
end
end
})
Example 2:
local args = getArgs(frame, {
valueFunc = function (key, value)
if type(value) == 'string' then
value = mw.ustring.lower(value)
if mw.ustring.find(value, '%S') then
return value
else
return nil
end
else
return value
end
end
})
|}
Also, please note that the valueFunc
function is called more or less every time an argument is requested from the args
table, so if you care about performance you should make sure you aren't doing anything inefficient with your code.
Frames and parent frames
Arguments in the args
table can be passed from the current frame or from its parent frame at the same time. To understand what this means, it is easiest to give an example. Let's say that we have a module called Module:ExampleArgs
. This module prints the first two positional arguments that it is passed.
local getArgs = require('Module:Arguments').getArgs
local p = {}
function p.main(frame)
local args = getArgs(frame)
return p._main(args)
end
function p._main(args)
local first = args[1] or ''
local second = args[2] or ''
return first .. ' ' .. second
end
return p
|}
Module:ExampleArgs
is then called by Template:ExampleArgs
, which contains the code {{#invoke:ExampleArgs|main|firstInvokeArg}}
. This produces the result "firstInvokeArg".
Now if we were to call Template:ExampleArgs
, the following would happen:
Code | Result |
---|---|
{{ExampleArgs}}
|
firstInvokeArg |
{{ExampleArgs|firstTemplateArg}}
|
firstInvokeArg |
{{ExampleArgs|firstTemplateArg|secondTemplateArg}}
|
firstInvokeArg secondTemplateArg |
There are three options you can set to change this behaviour: frameOnly
, parentOnly
and parentFirst
. If you set frameOnly
then only arguments passed from the current frame will be accepted; if you set parentOnly
then only arguments passed from the parent frame will be accepted; and if you set parentFirst
then arguments will be passed from both the current and parent frames, but the parent frame will have priority over the current frame. Here are the results in terms of Template:ExampleArgs
:
- frameOnly
Code | Result |
---|---|
{{ExampleArgs}}
|
firstInvokeArg |
{{ExampleArgs|firstTemplateArg}}
|
firstInvokeArg |
{{ExampleArgs|firstTemplateArg|secondTemplateArg}}
|
firstInvokeArg |
- parentOnly
Code | Result |
---|---|
{{ExampleArgs}}
|
|
{{ExampleArgs|firstTemplateArg}}
|
firstTemplateArg |
{{ExampleArgs|firstTemplateArg|secondTemplateArg}}
|
firstTemplateArg secondTemplateArg |
- parentFirst
Code | Result |
---|---|
{{ExampleArgs}}
|
firstInvokeArg |
{{ExampleArgs|firstTemplateArg}}
|
firstTemplateArg |
{{ExampleArgs|firstTemplateArg|secondTemplateArg}}
|
firstTemplateArg secondTemplateArg |
Notes:
- If you set both the
frameOnly
andparentOnly
options, the module won't fetch any arguments at all from #invoke. This is probably not what you want. - In some situations a parent frame may not be available, e.g. if getArgs is passed the parent frame rather than the current frame. In this case, only the frame arguments will be used (unless parentOnly is set, in which case no arguments will be used) and the
parentFirst
andframeOnly
options will have no effect.
Wrappers
The wrappers option is used to specify a limited number of templates as wrapper templates, that is, templates whose only purpose is to call a module. If the module detects that it is being called from a wrapper template, it will only check for arguments in the parent frame; otherwise it will only check for arguments in the frame passed to getArgs. This allows modules to be called by either #invoke or through a wrapper template without the loss of performance associated with having to check both the frame and the parent frame for each argument lookup.
For example, the only content of Template:Side box (excluding content in Template:Tag tags) is {{#invoke:Side box|main}}
. There is no point in checking the arguments passed directly to the #invoke statement for this template, as no arguments will ever be specified there. We can avoid checking arguments passed to #invoke by using the parentOnly option, but if we do this then #invoke will not work from other pages either. If this were the case, the Template:Para in the code {{#invoke:Side box|main|text=Some text}}
would be ignored completely, no matter what page it was used from. By using the wrappers
option to specify 'Template:Side box' as a wrapper, we can make {{#invoke:Side box|main|text=Some text}}
work from most pages, while still not requiring that the module check for arguments on the Template:Side box page itself.
Wrappers can be specified either as a string, or as an array of strings.
local args = getArgs(frame, {
wrappers = 'Template:Wrapper template'
})
local args = getArgs(frame, {
wrappers = {
'Template:Wrapper 1',
'Template:Wrapper 2',
-- Any number of wrapper templates can be added here.
}
})
Notes:
- The module will automatically detect if it is being called from a wrapper template's /sandbox subpage, so there is no need to specify sandbox pages explicitly.
- The wrappers option effectively changes the default of the frameOnly and parentOnly options. If, for example, parentOnly were explicitly set to false with wrappers set, calls via wrapper templates would result in both frame and parent arguments being loaded, though calls not via wrapper templates would result in only frame arguments being loaded.
- If the wrappers option is set and no parent frame is available, the module will always get the arguments from the frame passed to
getArgs
.
Writing to the args table
Sometimes it can be useful to write new values to the args table. This is possible with the default settings of this module. (However, bear in mind that it is usually better coding style to create a new table with your new values and copy arguments from the args table as needed.)
args.foo = 'some value'
It is possible to alter this behaviour with the readOnly
and noOverwrite
options. If readOnly
is set then it is not possible to write any values to the args table at all. If noOverwrite
is set, then it is possible to add new values to the table, but it is not possible to add a value if it would overwrite any arguments that are passed from #invoke.
Ref tags
This module uses metatables to fetch arguments from #invoke. This allows access to both the frame arguments and the parent frame arguments without using the pairs()
function. This can help if your module might be passed Template:Tag tags as input.
As soon as Template:Tag tags are accessed from Lua, they are processed by the MediaWiki software and the reference will appear in the reference list at the bottom of the article. If your module proceeds to omit the reference tag from the output, you will end up with a phantom reference – a reference that appears in the reference list but without any number linking to it. This has been a problem with modules that use pairs()
to detect whether to use the arguments from the frame or the parent frame, as those modules automatically process every available argument.
This module solves this problem by allowing access to both frame and parent frame arguments, while still only fetching those arguments when it is necessary. The problem will still occur if you use pairs(args)
elsewhere in your module, however.
Known limitations
The use of metatables also has its downsides. Most of the normal Lua table tools won't work properly on the args table, including the #
operator, the next()
function, and the functions in the table library. If using these is important for your module, you should use your own argument processing function instead of this module.
-- This module provides easy processing of arguments passed to Scribunto from #invoke.
-- It is intended for use by other Lua modules, and should not be called from #invoke directly.
local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local arguments = {}
local nilArg = {} -- Used for memoizing nil arguments in metaArgs.
-- Generate four different tidyVal functions, so that we don't have to check the options every time we call it.
local function tidyValDefault(key, val)
if type(val) == 'string' then
val = val:match('^%s*(.-)%s*$')
if val == '' then
return nil
else
return val
end
else
return val
end
end
local function tidyValTrimOnly(key, val)
if type(val) == 'string' then
return val:match('^%s*(.-)%s*$')
else
return val
end
end
local function tidyValRemoveBlanksOnly(key, val)
if type(val) == 'string' then
if val:find('%S') then
return val
else
return nil
end
else
return val
end
end
local function tidyValNoChange(key, val)
return val
end
function arguments.getArgs(frame, options)
checkType('getArgs', 1, frame, 'table', true)
checkType('getArgs', 2, options, 'table', true)
frame = frame or {}
options = options or {}
-- Get the arguments from the frame object if available. If the frame object is not available, we are being called
-- from another Lua module or from the debug console, so put the args in a special table so we can differentiate them.
local fargs, pargs, luaArgs
if type(frame.args) == 'table' and type(frame.getParent) == 'function' then
if not options.parentOnly then
fargs = frame.args
end
if not options.frameOnly then
pargs = frame:getParent().args
end
if options.parentFirst then
fargs, pargs = pargs, fargs
end
else
luaArgs = frame
end
-- Set up the args and metaArgs tables. args will be the one accessed from functions, and metaArgs will hold the actual arguments.
-- The metatable connects the two together.
local args, metaArgs, metatable = {}, {}, {}
setmetatable(args, metatable)
-- Generate the tidyVal function. If it has been specified by the user, we use that; if not, we choose one of four functions
-- depending on the options chosen. This is so that we don't have to call the options table every time the function is called.
local tidyVal = options.valueFunc
if tidyVal then
if type(tidyVal) ~= 'function' then
error("bad value assigned to option 'valueFunc' (function expected, got " .. type(tidyVal) .. ')', 2)
end
elseif options.trim ~= false then
if options.removeBlanks ~= false then
tidyVal = tidyValDefault
else
tidyVal = tidyValTrimOnly
end
else
if options.removeBlanks ~= false then
tidyVal = tidyValRemoveBlanksOnly
else
tidyVal = tidyValNoChange
end
end
local function mergeArgs(iterator, tables)
-- Accepts multiple tables as input and merges their keys and values into one table using the specified iterator.
-- If a value is already present it is not overwritten; tables listed earlier have precendence.
-- We are also memoizing nil values, but those values can be overwritten.
for _, t in ipairs(tables) do
for key, val in iterator(t) do
local metaArgsVal = metaArgs[key]
if metaArgsVal == nil or metaArgsVal == nilArg then
local tidiedVal = tidyVal(key, val)
if tidiedVal == nil then
metaArgs[key] = nilArg
else
metaArgs[key] = tidiedVal
end
end
end
end
end
-- Set the order of precedence of the argument tables. If the variables are nil, nothing will be added to the table,
-- which is how we avoid clashes between the frame/parent args and the Lua args.
local argTables = {fargs}
argTables[#argTables + 1] = pargs
argTables[#argTables + 1] = luaArgs
--[[
-- Define metatable behaviour. Arguments are memoized in the metaArgs table, and are only fetched from the
-- argument tables once. Nil arguments are also memoized using the nilArg variable in order to increase
-- performance. Also, we keep a record in the metatable of when pairs and ipairs have been called, so we
-- do not run pairs and ipairs on fargs and pargs more than once. We also do not run ipairs on fargs and
-- pargs if pairs has already been run, as all the arguments will already have been copied over.
--]]
metatable.__index = function (t, key)
local val = metaArgs[key]
if val ~= nil then
if val == nilArg then
return nil
else
return val
end
end
for _, argTable in ipairs(argTables) do
local argTableVal = tidyVal(key, argTable[key])
if argTableVal == nil then
metaArgs[key] = nilArg
else
metaArgs[key] = argTableVal
return argTableVal
end
end
return nil
end
metatable.__newindex = function (t, key, val)
if options.readOnly then
error('could not write to argument table key "' .. tostring(key) .. '"; the table is read-only', 2)
elseif options.noOverwrite and args[key] ~= nil then
error('could not write to argument table key "' .. tostring(key) .. '"; overwriting existing arguments is not permitted', 2)
elseif val == nil then
metaArgs[key] = nilArg -- Memoize nils.
else
metaArgs[key] = val
end
end
metatable.__pairs = function ()
if not metatable.donePairs then
mergeArgs(pairs, argTables)
metatable.donePairs = true
metatable.doneIpairs = true
end
return pairs(metaArgs)
end
metatable.__ipairs = function ()
if not metatable.doneIpairs then
mergeArgs(ipairs, argTables)
metatable.doneIpairs = true
end
return ipairs(metaArgs)
end
return args
end
return arguments