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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 of the same name but 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. A module should only provide '''one''' wrapper for '''one''' 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.


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
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
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end
end


-- Wrapper 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>The guidelines stated above do not apply to the following:
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


* Modules that serve as libraries for other modules; in such cases, there is no wrapper function other than the tester function. Example: [[Module:MOS]] and [[Module:Rational]]
function p._call_me(arg1, arg2, arg3)
* Modules that provide multiple functions, including wrapper functions, meant to be invoked by multiple templates; in such cases, the rule regarding one wrapper for one template does not apply. Example: [[Module:Rational]] and [[Module:Utils]]
    -- Code goes here
* Modules that provide only one function for other modules; in such cases, no wrapper functions are necessary. Example: [[Module:Yesno]]
end
* Template-based modules where writing a separate "main" function produces a short function; in such cases, the code for that function may be merged with the wrapper function. Example: [[Module:MOS scalesig]]
 
* Template-based modules whose wrapper function calls another module's functions; in such cases, no other functions are necessary. Example: [[Module:MOS scalesig]]
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.


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. 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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==== What to pass into a "main" function ====
==== What to pass into a "main" 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">
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
-- "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)
function p._call_me(arg1, arg2, arg3)
     -- Code goes here
     -- Code goes here
end
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">
</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.<syntaxhighlight lang="lua">
-- "Main" function to be called by wrapper or another module
-- "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)
function p._call_me(args)
     -- Get args here
     -- Get args here
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end
end
</syntaxhighlight>
</syntaxhighlight>
==== What to get out of a function ====
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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