Module:Unsubst

This is a helper module to facilitate a substituted template's transformation into a normal template transclusion.

Maintenance templates, such as {{Citation needed}} or {{More citations needed}}, should never be substituted. A trick to avoid that is to make a template substitute to its transcluded form.

Usage

To turn a template into a self-substituting template, wrap the existing template code with:

{{SAFESUBST:<noinclude />#invoke:Unsubst||$B=

[ … existing template code … ]

}}

The wikitext to display when not substed must be given as $B. All other parameters passed to the #invoke will be copied to the generated template invocation as default values. If the value of any of these default parameters is __DATE__, that value in the generated template invocation will be the current month and year.

Some templates have a <noinclude> but no matching </noinclude> at the end of the template. In such cases, the missing </noinclude> must be added before the ending }}.

Advanced

{{SAFESUBST:<noinclude />#invoke:Unsubst||$params=[ parameters ]|$aliases=[ aliases ]|$flags=[ flags ]|$B=

[ … existing template code … ]

}}

Due to Lua limitations, parameters are normally ordered randomly when the template is substituted. |$params= can be used in #invoke:Unsubst to list template parameters in order, comma-delimited (e.g. egg,bacon,sausage,cheese,spam). Numbered parameters should be before others in the list, then any remaining parameters are tacked onto the end of the generated invocation.

Parameter aliases can be listed in |$aliases= (and shouldn't be listed in |$params=), and will be replaced automatically. Each alias and its replacement should be formatted as alias>replacement, and each of those pairs should be comma-delimited as well (e.g. œuf>egg,melt>cheese). Note that this parameter can function with or without |$params=.

The |$flags= parameter can be used to modify other facets of the module's behaviour, and again, entries are comma-delimited. Valid flags are override (allows parameters in the #invoke: to take precedence over parameters in the original template invocation); keep-whitespace (prevents whitespace from being trimmed from unnamed parameters) and remove-empty (removes empty parameters).

These parameters can be manipulated using parser functions to provide more complicated options (note that in the parameters, any parser function or template or module invocation should also have SAFESUBST:<noinclude />).

Example

Consider a template Template:Example containing the following code:

{{SAFESUBST:<noinclude />#invoke:Unsubst||foo=bar |date=__DATE__ |$B=

[ … Template code goes here … ]

}}

Original	Result
{{subst:example}}	{{Example|date=November 2024}}
{{subst:example|foo=X}}	{{Example|foo=X|date=November 2024}}
{{subst:example|baz=X}}	{{Example|baz=X|date=November 2024}}
{{subst:example|date=January 2001}}	{{Example|foo=bar|date=January 2001}}

---

local p = {}

local specialParams = {
	['$N'] = 'template name',
	['$B'] = 'template content',
}

p[''] = function ( frame )
	if not frame:getParent() then
		error( '{{#invoke:Unsubst|unsubst}} makes no sense without a parent frame' )
	end
	for k, v in pairs( specialParams ) do
		if not frame.args[k] then
			error( '{{#invoke:Unsubst|unsubst}} requires parameter ' .. k .. ' (' .. v .. ')' )
		end
	end
	
	if mw.isSubsting() then
		---- substing
		-- Combine passed args with passed defaults
		local args = {}
		for k, v in pairs( frame.args ) do
			if not specialParams[k] then
				if v == '__DATE__' then
					v = mw.getContentLanguage():formatDate( 'F Y' )
				end
				args[k] = v
			end
		end
		for k, v in pairs( frame:getParent().args ) do
			args[k] = v
		end

		-- Now, build an equivalent template invocation
		-- First numbered args, then named
		local ret = '{{' .. frame.args['$N']
		for k, v in ipairs( args ) do
			if string.find( v, '=', 1, true ) then
				-- likely something like 1=foo=bar, we need to do it as a named arg
				break
			end
			ret = ret .. '|' .. v
			args[k] = nil
		end
		for k, v in pairs( args ) do
			ret = ret .. '|' .. k .. '=' .. v
		end
		
		return ret .. '}}'
	else
		---- Not substing
		-- Just return the "body"
		return frame.args['$B']
	end
end

return p