Module:unsubst

---

The following documentation is located at Module:unsubst/documentation. ^[edit]

Useful links: subpage list • links • transclusions • testcases • sandbox

This module protects templates and modules from being wrongly substituted.

Usage

There are two ways to use this module:

Protecting all templates in a module

First, put the following at the top of a module which contains functions designed to be called by {{#invoke:}}:

-- Prevent substitution.
if mw.isSubsting() then
	return require("Module:unsubst")
end

Second, edit each template which calls that module from:

{{#invoke:...|function|...}}

to:

{{safesubst:<noinclude/>#invoke:...|function|...}}

Note: this should only be used with modules that only return functions which are designed to be called by templates (not by other modules). If your module also returns functions (or other data) designed to be called by other modules, then the safest solution is to separate out the template functions into a separate module, usually in the format Module:.../templates (e.g. Module:links/templates). This is because unsubst prevents any functions or data in a module from being accessed during substitution, which will disrupt other modules which need to access your module while they are being substituted.

In templates

Template code can be wrapped as follows:

{{safesubst:<noinclude/>#invoke:unsubst|me|=
...
}}

local m_template_parser = require("Module:template parser")

local build_template = m_template_parser.buildTemplate
local concat = table.concat
local get_template_invocation_name = m_template_parser.getTemplateInvocationName
local is_valid_title = require("Module:pages").is_valid_title
local new_title = mw.title.new

local is_substing = mw.isSubsting()

local function unsubst_me(frame)
	return frame.args[""]
end

local function get_title(frame)
	local title = new_title(frame:getTitle())
	return is_valid_title(title) and title or
		-- This shouldn't happen.
		error("frame returned an invalid title")
end

local function serialize(title, args)
	return "{{" .. concat(build_template(title, args), "|") .. "}}"
end

local mt = {}

function mt:__index(entry_point)
	-- Cannot unsubst if not currently being substed.
	if not is_substing then
		local frame_title = mw.getCurrentFrame():getTitle()
		if frame_title ~= "Module:unsubst" then
			error(("[[%s]] should not call [[Module:unsubst]] unless mw.isSubsting() returns true"):format(frame_title))
		end
		-- Allow {{#invoke:unsubst|me|=...}}, but otherwise return nothing.
		return entry_point == "me" and unsubst_me or nil
	end
	return function(frame)
		local parent = frame:getParent()
		if parent:getTitle() ~= mw.title.getCurrentTitle().fullText then
			return serialize(get_template_invocation_name(get_title(parent)), parent.args)
		end
		local title = get_title(frame)
		return title.namespace == 828 and
			(serialize(("safesubst:<noinclude/>#invoke:%s|%s"):format(title.text, entry_point), frame.args)) or
			-- This shouldn't happen.
			error(("[[Module:unsubst]] cannot work if the current frame is not in the %s namespace, because the #invoke magic word requires it"):format(mw.site.namespaces[828].canonicalName))
	end
end

return setmetatable({}, mt)