Module:Example

This page, like the others here, exists for referencing by demonstrations, examples, etc.
It does not form part of the encyclopedia.
This is example documentation for the module, used for demonstrations and the like.
local p = {};     --All Lua modules on Wikipedia must begin by defining a variable 
                    --that will hold their externally accessible functions.
                    --Such variables can have whatever name you want and may 
                    --also contain various data as well as functions.
p.hello = function( frame )     --Add a function to "p".  
                                        --Such functions are callable in Wikipedia
                                        --via the #invoke command.
                                        --"frame" will contain the data that Wikipedia
                                        --sends this function when it runs. 
                                 -- 'Hello' is a name of your choice. The same name needs to be referred to when the module is used.
    
    local str = "Hello World!"  --Declare a local variable and set it equal to
                                --"Hello World!".  
    
    return str    --This tells us to quit this function and send the information in
                  --"str" back to Wikipedia.
    
end  -- end of the function "hello"
function p.hello_to(frame)		-- Add another function
	local name = frame.args[1]  -- To access arguments passed to a module, use `frame.args`
							    -- `frame.args[1]` refers to the first unnamed parameter
							    -- given to the module
	return "Hello, " .. name .. "!"  -- `..` concatenates strings. This will return a customized
									 -- greeting depending on the name given, such as "Hello, Fred!"
end
function p.count_fruit(frame)
	local num_bananas = frame.args.bananas -- Named arguments ({{#invoke:Example|count_fruit|foo=bar}}) are likewise 
	local num_apples = frame.args.apples   -- accessed by indexing `frame.args` by name (`frame.args["bananas"]`, or)
										   -- equivalently `frame.args.bananas`.
	return 'I have ' .. num_bananas .. ' bananas and ' .. num_apples .. ' apples'
										   -- Like above, concatenate a bunch of strings together to produce
										   -- a sentence based on the arguments given.
end

local function lucky(a, b) -- One can define custom functions for use. Here we define a function 'lucky' that has two inputs a and b. The names are of your choice.
	if b == 'yeah' then -- Condition: if b is the string 'yeah'. Strings require quotes. Remember to include 'then'.
		return a .. ' is my lucky number.' -- Outputs 'a is my lucky number.' if the above condition is met. The string concatenation operator is denoted by 2 dots.
	else -- If no conditions are met, i.e. if b is anything else, output specified on the next line.  'else' should not have 'then'.
		return a -- Simply output a.
	end -- The 'if' section should end with 'end'.
end -- As should 'function'.

function p.Name2(frame)
	-- The next five lines are mostly for convenience only and can be used as is for your module. The output conditions start on line 50.
	local pf = frame:getParent().args -- This line allows template parameters to be used in this code easily. The equal sign is used to define variables. 'pf' can be replaced with a word of your choice.
	local f = frame.args -- This line allows parameters from {{#invoke:}} to be used easily. 'f' can be replaced with a word of your choice.
	local M = f[1] or pf[1] -- f[1] and pf[1], which we just defined, refer to the first parameter. This line shortens them as 'M' for convenience. You could use the original variable names.
	local m = f[2] or pf[2] -- Second shortened as 'm'.
	local l = f.lucky or pf.lucky -- A named parameter 'lucky' is shortend as l. Note that the syntax is different from unnamed parameters.
	if m == nil then -- If the second parameter is not used.
		return 'Lonely' -- Outputs the string 'Lonely' if the first condition is met.
	elseif M > m then -- If the first condition is not met, this line tests a second condition: if M is greater than m.
		return lucky(M - m, l) -- If the condition is met, the difference is calculated and passed to the self defined function along with l. The output depends on whether l is set to 'yeah'.
	else
		return 'Be positive!'
	end
end

return p    --All modules end by returning the variable containing their functions to Wikipedia.
-- Now we can use this module by calling {{#invoke: Example | hello }},
-- {{#invoke: Example | hello_to | foo }}, or {{#invoke:Example|count_fruit|bananas=5|apples=6}}
-- Note that the first part of the invoke is the name of the Module's wikipage,
-- and the second part is the name of one of the functions attached to the 
-- variable that you returned.

-- The "print" function is not allowed in Wikipedia.  All output is accomplished
-- via strings "returned" to Wikipedia.
See also
