 | This Lua module is used in system messages
, and on
approximately 29,400,000 pages, or roughly 48% of all pages
.
Changes to it can cause immediate changes to the Wikipedia user interface.
To avoid major disruption and server load, any changes should be tested in the module's
/sandbox
or
/testcases
subpages, or in your own
module sandbox
. The tested changes can be added to this page in a single edit. Please discuss changes on the
talk page
before implementing them.
|
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
yesno
(
value
,
default
)
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.
local
yesno
=
require
(
'Module:Yesno'
)
Some input values always return
true
, and some always return
false
.
nil
values always return
nil
.
-- These always return true:
yesno
(
'yes'
)
yesno
(
'y'
)
yesno
(
'true'
)
yesno
(
't'
)
yesno
(
'on'
)
yesno
(
'1'
)
yesno
(
1
)
yesno
(
true
)
-- These always return false:
yesno
(
'no'
)
yesno
(
'n'
)
yesno
(
'false'
)
yesno
(
'f'
)
yesno
(
'off'
)
yesno
(
'0'
)
yesno
(
0
)
yesno
(
false
)
-- A nil value always returns nil:
yesno
(
nil
)
yesno
()
String values are converted to lower case before they are matched:
-- 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'
)
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.
-- These return nil:
yesno
(
nil
)
yesno
(
'foo'
)
yesno
({})
yesno
(
5
)
yesno
(
''
)
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
(
''
,
true
)
yesno
(
function
()
return
'This is a function.'
end
,
true
)
-- These return "bar":
yesno
(
'foo'
,
'bar'
)
yesno
({},
'bar'
)
yesno
(
5
,
'bar'
)
yesno
(
''
,
'bar'
)
yesno
(
function
()
return
'This is a function.'
end
,
'bar'
)
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:
yesno
(
nil
)
-- Returns nil.
yesno
(
'foo'
)
-- Returns nil.
yesno
(
nil
,
true
)
-- Returns nil.
yesno
(
nil
,
false
)
-- Returns nil.
yesno
(
'foo'
,
true
)
-- Returns true.
To get the binary
true
/
false
-only values, use code like:
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.