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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.
  • Arguments are fetched as needed, which can help avoid (some) problems with <ref>...</ref> tags.
  • 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 function makeInvokeFunc(funcName)
	return function (frame)
		local args = getArgs(frame)
		return p[funcName](args)
	end
end

local p = {}

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,
	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).

Examples 1 and 2 with type checking

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.

Module:ExampleArgs code
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

Note: if you set both the frameOnly and parentOnly options, the module won't fetch any arguments at all from #invoke. This is probably not what you want.

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 <ref>...</ref> tags as input.

As soon as <ref>...</ref> 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 no number that links 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.


--- Arguments invocation argument extractor for Scribunto modules.
--  It is intended for use by other Lua modules, and should not be
--  called from an invocation (`#invoke`) directly.
--  
--  This module supports the following features:
--   * Trimming and blank argument removal.
--   * Argument inheritance between child and parent frames.
--   * Argument extraction for external modules and console input.
--   * Options to customise argument extraction behaviour.
--  
--  @script             arguments
--  @release            stable
--  @note               The `args` table from the @{arguments.getArgs}
--                      function is a metatable for performance reasons.
--                      Thus, the table will not permit Lua table methods
--                      such as `#args`, @{next|next(args)}, and @{table}
--                      library functions.
--  @note               This module will eventually be adapted as a
--                      library in [[mw:gerrit:q/158323|MediaWiki
--                      core]], called as `require('getArgs')`. The core
--                      library will remove `options.parentOnly`.
--  @author             [[wikipedia:User:Mr. Stradivarius|Mr. Stradivarius]] (Wikipedia)
--  @author             [[wikipedia:User:Anomie|Anomie]] (Wikipedia)
--  @author             [[wikipedia:User:Jackmcbarn|Jackmcbarn]] (Wikipedia)
--  @author             [[User:Dessamator|Dessamator]]
--  @author             [[User:DarthKitty|DarthKitty]]
--  @attribution        [[wikipedia:Module:Arguments|Module:Arguments]] (Wikipedia)
--  @see                [[wikipedia:Module:Arguments|Original module on Wikipedia]]
--  @see                [[Module:Arguments/testcases|Test cases for this module]]
local arguments = {}

--  Module dependencies.
local i18n = require('Dev:I18n').loadMessages('Arguments')
local util = require('libraryUtil')
local checkType = util.checkType

-- Four different value tidying functions.
-- This way, we don't have to check the options every time we call them.

--- Default value tidying function.
--  Trims parameter values automatically if they are defined strings.
--  Treats blank strings as `nil`.
--  @function           tidyValDefault
--  @param              {string|number} key MediaWiki parameter key.
--  @param              {string|nil} val MediaWiki parameter value,
--                      or nil if `key` is an empty string or nil.
--  @local
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

--- Value tidying function that trims values.
--  Trims parameter values automatically if they are defined strings.
--  @function           tidyValTrimOnly
--  @param              {string|number} key MediaWiki parameter key.
--  @param              {string|nil} val MediaWiki parameter value.
--  @local
local function tidyValTrimOnly(key, val)
    if type(val) == 'string' then
        return val:match('^%s*(.-)%s*$')
    else
        return val
    end
end

--- Value tidying function that removes blanks.
--  Removes blank values from the arguments table.
--  @function           tidyValRemoveBlanksOnly
--  @param              {string|number} key MediaWiki parameter key.
--  @param              {string|nil} val MediaWiki parameter value,
--                      or nil if `key` is whitespace or nil.
--  @local
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

--- Value tidying function that returns original value.
--  Effectively a NOOP function that does no value processing.
--  @function           tidyValNoChange
--  @param              {string|number} key MediaWiki parameter key.
--  @param              {string|nil} val MediaWiki parameter value.
--  @local
local function tidyValNoChange(key, val)
    return val
end

--- Parent template title match checker.
--  @function           matchesTitle
--  @param              {string|number|nil} given Local prefixed page
--                      title, or MediaWiki article ID (`wgArticleId`).
--  @param              {string} title Title of parent template.
--  @return             {boolean} Whether the `given` ID/title matches
--                      the title of the parent template.
local function matchesTitle(given, title)
    local tp = type( given )
    return (tp == 'string' or tp == 'number') and mw.title.new( given ).prefixedText == title
end

--- Default argument translation metatable.
--  @table              translate_mt
--  @local
local translate_mt = { __index = function(t, k) return k end }

--- Main argument extraction utility.
--  Arguments are memoized once fetched for optimal performance,
--  as with the `frame.args` metatable in Scribunto core.
--  
--  The default argument lookup behaviour uses the child frame arguments
--  first, then the parent frame arguments. There are numerous frame
--  options to change this behaviour.
--  
--  The default value tidying behaviour trims parameter values if they
--  are defined strings and treats blank strings as `nil`. This can be
--  customised in the `getArgs` options.
--  
--  @param              {frame|table} frame Scribunto frame object or
--                      Lua arguments table, passed from an invocation
--                      or Lua logic such as `frame:getParent()`.
--                      If this parameter does not have an `args` field
--                      and a `getParent` method, `frame` is assumed
--                      to be a Lua arguments table, such as the
--                      arguments from a named arguments call.
--  @param[opt]         {table} options Extraction/processing options.
--  @param[opt]         {boolean} options.trim
--                      Whether to trim the blank arguments present in
--                      the arguments table. Accepts `false` only.
--                      Default: `true`.
--  @param[opt]         {boolean} options.removeBlanks
--                      Whether to remove blank arguments from the
--                      arguments table. Does not shift sequential
--                      arguments removed by the processing stage.
--                      Accepts `false` only. Default: `true`.
--  @param[opt]         {boolean} options.valueFunc
--                      Custom value tidying function for use if the
--                      `trim` and `removeBlanks` options don't cover
--                      the developer's argument processing use case.
--  @param[opt]         {boolean} options.frameOnly
--                      Only read arguments from child frame (the
--                      `frame` parameter - usually invocation frame).
--  @param[opt]         {boolean} options.parentOnly
--                      Only read arguments from `frame` parent (the
--                      `frame` parameter - usually template frame).
--  @param[opt]         {boolean} options.parentFirst
--                      Argument lookup in the `frame` parent first,
--                      prioritised over the invocation frame arguments.
--  @param[opt]         {table} options.wrappers
--                      Individual value or array of values, listing
--                      wrapper title name(s) or article ID(s) to permit
--                      parent argument lookup from.
--  @param[opt]         {string|number} options.wrapper
--                      Alias of `options.wrappers` - contains title
--                      name or article ID to permit parent argument
--                      lookup from.
--  @param[opt]         {boolean} options.readOnly
--                      Whether to restrict write permissions to the
--                      arguments table. When set to a truthy value,
--                      an error will be thrown on any write attempt.
--  @param[opt]         {boolean} options.noOverwrite
--                      Whether to restrict overwrite attempts on
--                      existing argument keys in the arguments table.
--                      When set to a truthy value, an error will be
--                      thrown on any write attempt that would result
--                      in an existing argument being overwritten.
--  @param[opt]         {table} options.translate
--                      Map of parameter name aliases to their canonical
--                      argument parameter names.
--  @param[opt]         {table} options.backtranslate
--                      Map of canonical parameter names to their
--                      argument parameter aliases.
--                      Supersedes `options.translate` if both options
--                      are in use.
--  @error[opt,317]     'bad value assigned to option "valueFunc"
--                      (function expected, got $type)'
--  @error[opt,407]     'could not write to argument table key "$key";
--                      the table is read-only'
--  @error[opt,409]     'could not write to argument table key "$key";
--                      overwriting existing arguments is not permitted'
--  @return             {table} Arguments extracted from invocation.
--                      The argument data is embedded as a metatable in
--                      the exported table and cannot be accessed with
--                      the `#` operator or @{table} library methods.
--                      However, the exported table can be written to if
--                      the `options.readOnly` flag parameter is not
--                      truthy.
--  @usage
--      
--      local getArgs = require('Module:Arguments').getArgs
--      function p.main(frame)
--          local args = getArgs(frame, {
--              wrapper = 'Template:<TEMPLATE>'
--          })
--          -- Use the args table here.
--          -- A common paradigm is `return p._main(args)`.
--          -- This allows other Lua modules to access the
--          -- main logic in a performant manner without a
--          -- frame object.
--      end
--      
--  @note               Reference tags in the form of `<ref>` will
--                      generate phantom references when calling the
--                      @{pairs} iterator on the arguments table,
--                      **IF** the `<ref>` tag does not appear in the
--                      dependent module's wikitext output.
function arguments.getArgs(frame, options)
    checkType('getArgs', 1, frame, 'table', true)
    checkType('getArgs', 2, options, 'table', true)
    frame = frame or {}
    options = options or {}

    -- Set up argument translation.
    options.translate = options.translate or {}
    if getmetatable(options.translate) == nil then
        setmetatable(options.translate, translate_mt)
    end
    if options.backtranslate == nil then
        options.backtranslate = {}
        for k,v in pairs(options.translate) do
            options.backtranslate[v] = k
        end
    end
    if options.backtranslate and getmetatable(options.backtranslate) == nil then
        setmetatable(options.backtranslate, {
            __index = function(t, k)
                if options.translate[k] ~= k then
                    return nil
                else
                    return k
                end
            end
        })
    end

    -- Get the argument tables. If we were passed a valid frame object,
    -- get the frame arguments (fargs) and the parent frame arguments
    -- (pargs), depending on the options set and on the parent frame's
    -- availability. If we weren't passed a valid frame object, we are
    -- being called from another Lua module or from the debug console,
    -- so assume that we were passed a table of args directly, and
    -- assign it to a new variable (luaArgs).
    local fargs, pargs, luaArgs
    options.wrappers = options.wrappers or options.wrapper
    if
        type(frame.args) == 'table' and
        type(frame.getParent) == 'function'
    then
        -- The wrappers option makes Module:Arguments look up
        -- arguments in either the frame argument table or the
        -- parent argument table, but not both. This means that
        -- users can use either the #invoke syntax or a wrapper
        -- template without the loss of performance associated
        -- with looking arguments up in both the frame and the
        -- parent frame.
        -- The arguments will be fetched from the parent frame if
        -- the parent frame's title is present in options.wrapper;
        -- otherwise it will look up arguments in the frame object
        -- passed to getArgs.
        if options.wrappers then
            local parent = frame:getParent()
            if not parent then
                fargs = frame.args
            else
                local title = parent:getTitle():gsub('/sandbox$', '')
                local found = false
                if matchesTitle(options.wrappers, title) then
                    found = true
                elseif type(options.wrappers) == 'table' then
                    for _,v in pairs(options.wrappers) do
                        if matchesTitle(v, title) then
                            found = true
                            break
                        end
                    end
                end

                -- We test for false specifically here so that nil (the
                -- default) acts like true.
                if found or options.frameOnly == false then
                    pargs = parent.args
                end
                if not found or options.parentOnly == false then
                    fargs = frame.args
                end
            end
        -- When options.wrapper isn't set, check the other options.
        else
            if not options.parentOnly then
                fargs = frame.args
            end
            if not options.frameOnly then
                local parent = frame:getParent()
                pargs = parent and parent.args or nil
            end
        end
        if options.parentFirst then
            fargs, pargs = pargs, fargs
        end
    else
        luaArgs = frame
    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

    -- 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(i18n:msg('error-value-func', 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

    -- Set up the args, metaArgs and nilArgs tables. args will be the one
    -- accessed from functions, and metaArgs will hold the actual arguments. Nil
    -- arguments are memoized in nilArgs, and the metatable connects all of them
    -- together.
    local args, metaArgs, nilArgs, metatable = {}, {}, {}, {}
    setmetatable(args, metatable)

    -- Accepts multiple tables as input and merges their keys and values
    -- into one table. If a value is already present it is not overwritten;
    -- tables listed earlier have precedence. We are also memoizing nil
    -- values, which can be overwritten if they are 's' (soft).
    local function mergeArgs(tables)
        for _, t in ipairs(tables) do
            for key, val in pairs(t) do
                if metaArgs[key] == nil and nilArgs[key] ~= 'h' then
                    local tidiedVal = tidyVal(key, val)
                    if tidiedVal == nil then
                        nilArgs[key] = 's'
                    else
                        metaArgs[key] = tidiedVal
                    end
                end
            end
        end
    end

    -- Define metatable behaviour. Arguments are memoized in the metaArgs table,
    -- and are only fetched from the argument tables once. Fetching arguments
    -- from the argument tables is the most resource-intensive step in this
    -- module, so we try and avoid it where possible. For this reason, nil
    -- arguments are also memoized, in the nilArgs table. 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 the argument tables 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.

    -- Fetches an argument when the args table is indexed. First we check
    -- to see if the value is memoized, and if not we try and fetch it from
    -- the argument tables. When we check memoization, we need to check
    -- metaArgs before nilArgs, as both can be non-nil at the same time.
    -- If the argument is not present in metaArgs, we also check whether
    -- pairs has been run yet. If pairs has already been run, we return nil.
    -- This is because all the arguments will have already been copied into
    -- metaArgs by the mergeArgs function, meaning that any other arguments
    -- must be nil.
    metatable.__index = function (t, key)
        if type(key) == 'string' then
            key = options.translate[key]
        end
        local val = metaArgs[key]
        if val ~= nil then
            return val
        elseif metatable.donePairs or nilArgs[key] then
            return nil
        end
        for _, argTable in ipairs(argTables) do
            local argTableVal = tidyVal(key, argTable[key])
            if argTableVal ~= nil then
                metaArgs[key] = argTableVal
                return argTableVal
            end
        end
        nilArgs[key] = 'h'
        return nil
    end

    metatable.__newindex = function (t, key, val)
        -- This function is called when a module tries to add a new
        -- value to the args table, or tries to change an existing
        -- value.
        if type(key) == 'string' then
            key = options.translate[key]
        end
        if options.readOnly then
            error(i18n:msg('error-write-permission', tostring(key)), 2)
        elseif options.noOverwrite and args[key] ~= nil then
            error(i18n:msg('error-overwrite-permission', tostring(key)), 2)
        elseif val == nil then
            -- If the argument is to be overwritten with nil, we need to erase
            -- the value in metaArgs, so that __index, __pairs and __ipairs do
            -- not use a previous existing value, if present; and we also need
            -- to memoize the nil in nilArgs, so that the value isn't looked
            -- up in the argument tables if it is accessed again.
            metaArgs[key] = nil
            nilArgs[key] = 'h'
        else
            metaArgs[key] = val
        end
    end

    local function translatenext(invariant)
        local k, v = next(invariant.t, invariant.k)
        invariant.k = k
        if k == nil then
            return nil
        elseif type(k) ~= 'string' or not options.backtranslate then
            return k, v
        else
            local backtranslate = options.backtranslate[k]
            if backtranslate == nil then
                -- Skip this one. This is a tail call, so this
                -- won't cause stack overflow.
                return translatenext(invariant)
            else
                return backtranslate, v
            end
        end
    end

    -- This metamethod is called when pairs is run on the args table.
    metatable.__pairs = function ()
        if not metatable.donePairs then
            mergeArgs(argTables)
            metatable.donePairs = true
        end
        return translatenext, { t = metaArgs }
    end

    -- This custom `ipairs`-style iterator uses our __index metamethod.
    local function inext(t, i)
        local v = t[i + 1]
        if v ~= nil then
            return i + 1, v
        end
    end

    -- This metamethod is called when ipairs is run on the args table.
    metatable.__ipairs = function (t)
        return inext, t, 0
    end

    return args
end

return arguments
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