Arguments/doc

This module provides easy processing of arguments passed from **Script error: No such module "String/Templates".**. It is a meta-module, meant for use by other modules, and should not be called from **Script error: No such module "String/Templates".** directly. Its features include:

* Easy trimming of arguments and removal of blank arguments.
* Arguments can be passed by both the current frame and by the parent frame at the same time. (More details below.)
* Arguments can be passed in directly from another Lua module or from the debug console.
* Most features can be customized.

## Basic use

First, you need to load the module. It contains one function, named Template:M.

**Script error: No such module "String/Templates".**

In the most basic scenario, you can use getArgs inside your main function. The variable Template:P is a table containing the arguments from **Script error: No such module "String/Templates".**. (See below for details.)

**Script error: No such module "String/Templates".**

### Recommended practice

However, the recommended practice is to use a function just for processing arguments from **Script error: No such module "String/Templates".**. This means that if someone calls your module from another Lua module you don't have to have a frame object available, which improves performance.

**Script error: No such module "String/Templates".**

### Multiple functions

If you want multiple functions to use the arguments, and you also want them to be accessible from **Script error: No such module "String/Templates".**, you can use a wrapper function.

**Script error: No such module "String/Templates".**

### Options

The following options are available. They are explained in the sections below.

**Script error: No such module "String/Templates".**

### Trimming and removing blanks

Blank arguments often trip up coders new to converting MediaWiki templates to Lua. In template syntax, blank strings and strings consisting only of whitespace are considered false. However, in Lua, blank strings and strings consisting of whitespace are considered true. This means that if you don't pay attention to such arguments when you write your Lua modules, you might treat something as true that should actually be treated as false. To avoid this, by default this module removes all blank arguments.

Similarly, whitespace can cause problems when dealing with positional arguments. Although whitespace is trimmed for named arguments coming from **Script error: No such module "String/Templates".**, it is preserved for positional arguments. Most of the time this additional whitespace is not desired, so this module trims it off by default.

However, sometimes you want to use blank arguments as input, and sometimes you want to keep additional whitespace. This can be necessary to convert some templates exactly as they were written. If you want to do this, you can set the Template:P and Template:P arguments to **Script error: No such module "String/Templates".**.

**Script error: No such module "String/Templates".**

### Custom formatting of arguments

Sometimes you want to remove some blank arguments but not others, or perhaps you might want to put all of the positional arguments in lower case. To do things like this you can use the **Script error: No such module "String/Templates".** option. The input to this option must be a function that takes two parameters, **Script error: No such module "String/Templates".** and **Script error: No such module "String/Templates".**, and returns a single value. This value is what you will get when you access the field **Script error: No such module "String/Templates".** in the **Script error: No such module "String/Templates".** table.

Example 1: this function preserves whitespace for the first positional argument, but trims all other arguments and removes all other blank arguments.
**Script error: No such module "String/Templates".**

Example 2: this function removes blank arguments and converts all arguments to lower case, but doesn't trim whitespace from positional parameters.
**Script error: No such module "String/Templates".**

Note: the above functions will fail if passed input that is not of type **Script error: No such module "String/Templates".** or **Script error: No such module "String/Templates".**. This might be the case if you use the Template:M function in the main function of your module, and that function is called by another Lua module. In this case, you will need to check the type of your input. This is not a problem if you are using a function specially for arguments from **Script error: No such module "String/Templates".** (i.e. you have Template:M and Template:M functions, or something similar).

Example 1:
**Script error: No such module "String/Templates".**

Example 2:
**Script error: No such module "String/Templates".**

Also, please note that the Template:M function is called more or less every time an argument is requested from the Template:P table, so if you care about performance you should make sure you aren't doing anything inefficient with your code.

### Frames and parent frames

Arguments in the Template:P table can be passed from the current frame or from its parent frame at the same time. To understand what this means, it is easiest to give an example. Let's say that we have a module called **Script error: No such module "String/Templates".**. This module prints the first two positional arguments that it is passed.

**Script error: No such module "String/Templates".**

**Script error: No such module "String/Templates".** is then called by **Script error: No such module "String/Templates".**, which contains the code **Script error: No such module "String/Templates".**. This produces the result "firstInvokeArg".

Now if we were to call **Script error: No such module "String/Templates".**, the following would happen:

 **Script error: No such module "String/Templates".** | firstInvokeArg secondTemplateArg

There are three options you can set to change this behavior: Template:P, Template:P and Template:P. If you set Template:P then only arguments passed from the current frame will be accepted; if you set Template:P then only arguments passed from the parent frame will be accepted; and if you set Template:P then arguments will be passed from both the current and parent frames, but the parent frame will have priority over the current frame. Here are the results in terms of `{{ExampleArgs}}`:

`frameOnly`

 **Script error: No such module "String/Templates".** | firstInvokeArg

parentOnly

 **Script error: No such module "String/Templates".** | firstTemplateArg secondTemplateArg

parentFirst

 **Script error: No such module "String/Templates".** | firstTemplateArg secondTemplateArg

Notes:

1. If you set both the Template:P and Template:P options, the module won't fetch any arguments at all from **Script error: No such module "String/Templates".**. This is probably not what you want.
2. In some situations a parent frame may not be available, e.g. if getArgs is passed the parent frame rather than the current frame. In this case, only the frame arguments will be used (unless parentOnly is set, in which case no arguments will be used) and the Template:P and Template:P options will have no effect.

### Wrappers

The *wrappers* option is used to specify a limited number of templates as *wrapper templates*, that is, templates whose only purpose is to call a module. If the module detects that it is being called from a wrapper template, it will only check for arguments in the parent frame; otherwise it will only check for arguments in the frame passed to getArgs. This allows modules to be called by either **Script error: No such module "String/Templates".** or through a wrapper template without the loss of performance associated with having to check both the frame and the parent frame for each argument lookup.

Wrappers can be specified either as a string, or as an array of strings.

**Script error: No such module "String/Templates".**

**Script error: No such module "String/Templates".**

Notes:

1. The module will automatically detect if it is being called from a wrapper template's /sandbox subpage, so there is no need to specify sandbox pages explicitly.
2. The *wrappers* option effectively changes the default of the *frameOnly* and *parentOnly* options. If, for example, *parentOnly* were explicitly set to false with *wrappers* set, calls via wrapper templates would result in both frame and parent arguments being loaded, though calls not via wrapper templates would result in only frame arguments being loaded.
3. If the *wrappers* option is set and no parent frame is available, the module will always get the arguments from the frame passed to Template:M.

### Writing to the args table

Sometimes it can be useful to write new values to the args table. This is possible with the default settings of this module. (However, bear in mind that it is usually better coding style to create a new table with your new values and copy arguments from the args table as needed.)

**Script error: No such module "String/Templates".**

It is possible to alter this behaviour with the Template:P and Template:P options. If Template:P is set then it is not possible to write any values to the args table at all. If Template:P is set, then it is possible to add new values to the table, but it is not possible to add a value if it would overwrite any arguments that are passed from #invoke.

### Ref tags

This module uses metatables to fetch arguments from #invoke. This allows access to both the frame arguments and the parent frame arguments without using the Template:M function. This can help if your module might be passed Template:Tag tags as input.

As soon as Template:Tag tags are accessed from Lua, they are processed by the MediaWiki software and the reference will appear in the reference list at the bottom of the article. If your module proceeds to omit the reference tag from the output, you will end up with a phantom reference – a reference that appears in the reference list but without any number linking to it. This has been a problem with modules that use Template:M to detect whether to use the arguments from the frame or the parent frame, as those modules automatically process every available argument.

This module solves this problem by allowing access to both frame and parent frame arguments, while still only fetching those arguments when it is necessary. The problem will still occur if you use Template:M elsewhere in your module, however.

### Known limitations

The use of metatables also has its downsides. Most of the normal Lua table tools won't work properly on the args table, including the **Script error: No such module "String/Templates".** operator, the Template:M function, and the functions in the table library. If using these is important for your module, you should use your own argument processing function instead of this module.
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