Module:Yesno/doc: Difference between revisions
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| pre-alpha | prealpha | pa = This module is rated as pre-alpha. It is unfinished, and may or may not be in active development. It should not be used from article namespace pages. Modules remain pre-alpha until the original editor (or someone who takes one over if it is abandoned for some time) is satisfied with the basic structure.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | alpha | a = This module is rated as alpha. It is ready for third-party input, and may be used on a few pages to see if problems arise, but should be watched. Suggestions for new features or changes in their input and output mechanisms are welcome.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | beta | b = This module is rated as beta, and is ready for widespread use. It is still new and should be used with some caution to ensure the results are as expected.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | release | r | general | g = This module is rated as ready for general use. It has reached a mature form and is thought to be relatively bug-free and ready for use wherever appropriate. It is ready to mention on help pages and other Wikipedia resources as an option for new users to learn. To reduce server load and bad output, it should be improved by sandbox testing rather than repeated trial-and-error editing.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | protected | protect | p = This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is protected from editing.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | semiprotected | semiprotect | semi = This module is subject to page protection. It is a highly visible module in use by a very large number of pages, or is substituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it is semi-protected from editing.{{#switch: doc|doc|sandbox= | {{#ifeq: | true | | }} }} | #default = Script error: No such module "Error".}} |
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This module provides a consistent interface for processing boolean or boolean-style string input. While Lua allows the true
and false
boolean values, wikicode templates can only express boolean values through strings such as "yes", "no", etc. This module processes these kinds of strings and turns them into boolean input for Lua to process. It also returns nil
values as nil
, to allow for distinctions between nil
and false
. The module also accepts other Lua structures as input, i.e. booleans, numbers, tables, and functions. If it is passed input that it does not recognise as boolean or nil
, it is possible to specify a default value to return.
Syntax
<syntaxhighlight lang="lua">yesno(value, default)</syntaxhighlight>
value
is the value to be tested. Boolean input or boolean-style input (see below) always evaluates to either true
or false
, and nil
always evaluates to nil
. Other values evaluate to default
.
Usage
First, load the module. Note that it can only be loaded from other Lua modules, not from normal wiki pages. For normal wiki pages you can use {{yesno}} instead.
<syntaxhighlight lang="lua"> local yesno = require('Module:Yesno') </syntaxhighlight>
Some input values always return true
, and some always return false
. nil
values always return nil
.
<syntaxhighlight lang="lua"> -- These always return true: yesno('yes') yesno('y') yesno('true') yesno('t') yesno('1') yesno(1) yesno(true)
-- These always return false: yesno('no') yesno('n') yesno('false') yesno('f') yesno('0') yesno(0) yesno(false)
-- A nil value always returns nil: yesno(nil) </syntaxhighlight>
String values are converted to lower case before they are matched:
<syntaxhighlight lang="lua"> -- These always return true: yesno('Yes') yesno('YES') yesno('yEs') yesno('Y') yesno('tRuE')
-- These always return false: yesno('No') yesno('NO') yesno('nO') yesno('N') yesno('fALsE') </syntaxhighlight>
Undefined input ('foo')
You can specify a default value if yesno receives input other than that listed above. If you don't supply a default, the module will return nil
for these inputs.
<syntaxhighlight lang="lua"> -- These return nil: yesno('foo') yesno({}) yesno(5) yesno(function() return 'This is a function.' end) yesno(nil, true) yesno(nil, 'bar')
-- These return true: yesno('foo', true) yesno({}, true) yesno(5, true) yesno(function() return 'This is a function.' end, true)
-- These return "bar": yesno('foo', 'bar') yesno({}, 'bar') yesno(5, 'bar') yesno(function() return 'This is a function.' end, 'bar') </syntaxhighlight>
Note that the empty string also functions this way: <syntaxhighlight lang="lua"> yesno() -- Returns nil. yesno(, true) -- Returns true. yesno(, 'bar') -- Returns "bar". </syntaxhighlight>
Although the empty string usually evaluates to false in wikitext, it evaluates to true in Lua. This module prefers the Lua behaviour over the wikitext behaviour. If treating the empty string as false is important for your module, you will need to convert empty strings to a value that evaluates to false before passing them to this module. In the case of arguments received from wikitext, this can be done by using Module:Arguments.
Handling nil results
By definition
- <syntaxhighlight lang="lua">
yesno(nil) -- Returns nil. yesno('foo') -- Returns nil. yesno(nil, true) -- Returns nil. yesno(nil, false) -- Returns nil. yesno('foo', true) -- Returns true. </syntaxhighlight>
To get the binary <syntaxhighlight lang="lua" inline>true/false</syntaxhighlight>-only values, use code like: <syntaxhighlight lang="lua"> myvariable = yesno(value) or false -- When value is nil, result is false. myvariable = yesno(value) or true -- When value is nil, result is true. myvariable = yesno('foo') or false -- Unknown string returns nil, result is false. myvariable = yesno('foo', true) or false -- Default value (here: true) applies, result is true. </syntaxhighlight>