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Parts of it are adapted for use on the wiki, with details on specific conventions. If a specific convention is missing, fall back to that described in the Luarocks style guide.
Parts of it are adapted for use on the wiki, with details on specific conventions. If a specific convention is missing, fall back to that described in the Luarocks style guide.
== Provisional additions for version 2 ==
Consistency with param names, including spelling:
* Define all param names at the module level, not the template level
* Use snake_case for all param names throughout; anything remotely close to snake_case is normalized to snake_case
* "debug" and "nocat" are reserved for toggling categories; the use of "debug" this way has already been the standard


== Preliminaries ==
== Preliminaries ==
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=== Naming and declaring variables ===
=== Naming and declaring variables ===


Variable names should be short and descriptive, written <code>snake_case</code>. Exceptions to this include counter variables, like with <code>i</code> in for loops. Boolean variables are prefixed with <code>is_</code>. Constants are named using <code>TRAIN_CASE</code>.
Variable names should be short and descriptive, written in <code>snake_case</code>. Exceptions to this include counter variables, like with <code>i</code> in for loops. Boolean variables are prefixed with <code>is_</code> or <code>has_</code> wherever possible. Constants are named using <code>TRAIN_CASE</code>.


All variable declarations should start with <code>local</code>.
All variable declarations should start with <code>local</code>.
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=== Line lengths ===
=== Line lengths ===


The 80-column limit is to be observed wherever possible for both comments and code, except for cases where strings, inline comments, or function calls are too long.
The 80-column limit should be observed wherever possible for both comments and code, except for cases where strings, inline comments, or function calls are too long.


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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=== Naming, declaring, and calling functions ===
=== Naming, declaring, and calling functions ===


As with variables, functions are named using <code>snake_case</code>. Functions that return a boolean variable are prefixed with <code>is_</code>''.''
As with variables, functions are named using <code>snake_case</code>. Functions that return a boolean variable are prefixed with <code>is_</code> or <code>has_</code>.


''tbd''
''tbd''
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=== Use of functions ===
=== Use of functions ===


===== "Main", wrapper, and tester functions =====
===== Modules that implement templates =====
Templates should consist of at least two functions: a "main" function prefixed with an underscore, and a wrapper function without an underscore.
Modules that implement templates should consist of at least two functions: a "main" function prefixed with an underscore, and a wrapper function of the same name but without an underscore.


The use of a wrapper and "main" function allows for a module to be used directly in another module or indirectly through its corresponding template.
The use of a wrapper and "main" function allows for a module to be used directly in another module or indirectly through its corresponding template. A module should only provide '''one''' wrapper for '''one''' template. If the "main" function is short enough, its code may be merged with the wrapper function.


For testing purposes, a tester function may be added, which is itself a wrapper that calls the main function.<syntaxhighlight lang="lua">
A tester function may be added for testing purposes, which is itself a wrapper that also calls the "main" function. This allows it to be tested using the in-browser console by calling mw.logObject(p.tester()). Tester functions may be removed if the "main" function is determined to be functional under expected conditions.<syntaxhighlight lang="lua">-- "Main" function to be called by wrapper or another module
-- "Main" function to be called by wrapper or another module
function p._call_me(args)
function p._call_me(args)
     return "something" .. args["something"]
     return "something" .. args["something"]
end
end


-- Function to be called by template
-- Wrapper function; to be called by template using {{#invoke}}
function p.call_me(frame)
function p.call_me(frame)
     return p._call_me(frame.args)
     return p._call_me(frame.args)
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     local args = { ["something"] = 123 }
     local args = { ["something"] = 123 }
     return p._call_me(args)
     return p._call_me(args)
end</syntaxhighlight><syntaxhighlight lang="lua">-- Wrapper function; to be called by template
function p.call_me(frame)
    local arg = frame.args["arg"]
   
    -- Code goes here
   
    return call_me(arg)
end</syntaxhighlight>
==== Modules that serve as libraries ====
Modules that serve as libraries for other modules do not need a wrapper function, apart from the tester. Examples include [[Module:MOS]], [[Module:Rational]], and [[Module:Utils]].
Modules that serve as libraries for multiple, related templates may provide multiple wrapper functions. If a module provides multiple wrappers that each call a corresponding function, the name of the function called within the wrapper must be prefixed with an underscore.<syntaxhighlight lang="lua">-- MAIN FUNCTIONS
-- Usable by other modules
function p._call_me(arg1, arg2, arg3)
    -- Code goes here
end
end
</syntaxhighlight>These guidelines do not apply for simple modules, or modules that only provide one function.
 
function p._truncate(arg1)
    -- Code goes here
end
 
-- WRAPPER FUNCTIONS
-- Usable by templates with {{#invoke}}
 
function p._call_me(frame)
    return p._clamp(frame.args["arg1"], frame.args["arg2"], frame.args["arg3"])
end
 
function p.truncate(frame)
    return p._truncate(frame.args["arg1"])
end</syntaxhighlight>Modules that only provide one function may simply consist of that function as a return value. Example: [[Module:Yesno]].


==== Helper functions ====
==== Helper functions ====
For code readability and code reusability within the module, the use of helper functions is recommended.
For code readability and code reusability within the module, the use of helper functions is recommended.


Helper functions may be nested within the calling function if those helpers only serve that function. This rule may be disregarded for testing purposes. Nested functions have access to the variables and parameters of the outer function, so an equivalent nested function may require fewer parameters.<syntaxhighlight lang="lua">function some_function(args)
Ideally, helper functions should be nested within the calling function if those helpers only serve that function, but this rule may be disregarded for testing purposes, or for helper functions needed by more than one function. Nested functions have access to the variables and parameters of the outer function, so an equivalent nested function may require fewer parameters.<syntaxhighlight lang="lua">function p._call_me(args)
     -- Get args here
     -- Get args here
     local arg1 = args["Arg 1"]
     local arg1 = args["Arg 1"]
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end</syntaxhighlight>
end</syntaxhighlight>


==== Modules that serve as libraries for other modules ====
==== What to pass into a "main" function ====
Modules that serve to provide functions to other libraries do not need any wrapper functions apart from a tester function.
For an underscore-prefixed "main" function, if its expected inputs is determined to be fixed (for example, no new features are expected to ever be added), the function may accept them individually.<syntaxhighlight lang="lua">-- "Main" function to be called by wrapper or another module
-- Function signature consists of three args and the return value (not shown)
function p._call_me(arg1, arg2, arg3)
    -- Code goes here
end</syntaxhighlight>If there is large amounts of input, or if the number of inputs is not known, the function should have a single parameter that is a table of passed-in arguments. This allows for expansion of the template's inputs without making the function signature any larger.<syntaxhighlight lang="lua">
-- "Main" function to be called by wrapper or another module
-- Function signature consists of one table and the output (not shown)
function p._call_me(args)
    -- Get args here
    local arg1 = args["args1"]
    local arg2 = args["args2"]
    local arg3 = args["args3"]
   
    -- Code goes here
end
</syntaxhighlight>


==== Modules that provide wrappers for more than one template ====
==== What to get out of a function ====
Unless the wrapper functions encapsulate very simple tasks, a module should only ever provide '''one''' wrapper function for '''one''' template.
Most functions should return something (a value, a string, a table, or more than one of those things), with the exception of functions that change the contents of a table. Modules that implement templates typically return a string that represents something that can be interpreted as wikitext. Guidance on how to create such strings is explained in later sections.


=== Concatenating strings ===
=== Concatenating strings ===
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| ee
| ee
| ff
| ff
|}</syntaxhighlight>'''Avoid'''<syntaxhighlight lang="wikitext">
|}</syntaxhighlight>
{| class="wikitable"
 
'''Avoid'''
 
<syntaxhighlight lang="wikitext">{| class="wikitable"
|+ Caption text
|+ Caption text
|-
|-
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| dd || ee || ff
| dd || ee || ff
|}
|}
</syntaxhighlight>
=== <code>ipairs</code> versus <code>pairs</code> versus <code>for</code> loop ===
<syntaxhighlight lang="lua">
local sometable = { "egg", "bread", "banana", nil, "milk" }


-- As a for loop
-- Order is guaranteed, but where to stop and start is needed
-- Iterates through all numeric indices, even if values are nil
for i = 1, #sometable do
    -- Code goes here
end
-- As a for loop using ipairs
-- Order is guaranteed, in ascending order
-- Iterates through numeric keys/indices, but stops at the first value of nil encountered
-- Obviates using sometable[i], as value has the same... value
for index, value in ipairs(sometable) do
    -- Code goes here
end
-- As a for loop using pairs
-- Order is not guaranteed
-- Iterates through numeric and non-numeric keys
for key, value in pairs(sometable) do
    -- Code goes here
end
</syntaxhighlight>
</syntaxhighlight>


== Templates and modules ==
== Templates and modules ==


=== Param names ===
=== Param names ===
Capitalized, short, and descriptive parameter names are preferred wherever possible, such as <code>Scale Signature</code>, and not <code>scalesig</code> or <code>ssg</code>. Non-capitalized parameter names are used for debugging, testing, or meta-use (parameters used to build other templates and typically would never be seen in normal use), such as <code>name</code> and <code>debug</code>.
Capitalized, short, and descriptive parameter names are preferred wherever possible, such as <code>Scale Signature</code>, and not <code>scalesig</code> or <code>ssg</code>.
 
Non-capitalized parameter names are used for debugging, testing, or meta-use (parameters used to build other templates and typically would never be seen in normal use), such as <code>name</code> and <code>debug</code>. Templates with simple usage can use non-capitalized parameter names throughout.
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