Editing Module:Yesno/doc (section)

===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. (XXX: when value is false, 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>

Better suggestions:
<syntaxhighlight lang="lua">
local myvariable = yesno(value)
if myvariable == nil then -- value is nil or an unrecognized string
    myvariable = true
end

-- more efficient when value is nil, but more verbose
-- (note the default result has to be written twice)
local myvariable
if value == nil then
    myvariable = true
else
    myvariable = yesno(value, true)
end

-- Terse coding when the default is false:
myvariable = yesno(value or false, false)
-- if value is nil, yesno() is called with false instead; result is false.
-- If value is 'foo', yesno() is called with 'foo'; 'foo' makes no sense, so the default (false) is returned.
-- if value is 'yes' or 'no', yesno() is called with 'yes' or 'no'; result is true or false.

-- Terse coding when the default is true:
myvariable = yesno(value or true, true)
-- if value is nil, yesno() is called with true instead; result is true.
-- If value is 'foo', yesno() is called with 'foo'; 'foo' makes no sense, so the default (true) is returned.
-- if value is 'yes' or 'no', yesno() is called with 'yes' or 'no'; result is true or false.
</syntaxhighlight><!--
--><includeonly>{{sandbox other||
[[Category:Lua metamodules]]
}}</includeonly>
<noinclude>
[[Category:Module documentation pages]]
</noinclude>