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I have just made many attempts, there is no code that handles the "nil" case properly AND simply; as a reminder, Lua's "and/or pseudo-ternary" doesn't exactly behaves like real "?:" ternaries, and that's problematic here; I would suggest to handle the "nil" case really separately, e.g. « if value == nil then myvariable = true/false else myvariable = yesno(value) end », as it's the simplest actually |
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<noinclude>{{pp|small=yes}}
</noinclude>{{used in system}}
{{Module rating|protected}}
{{cascade-protected template|page=module}}
This module provides a consistent interface for processing boolean or boolean-style string input. While Lua allows the <code>true</code> and <code>false</code> 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 <code>nil</code> values as <code>nil</code>, to allow for distinctions between <code>nil</code> and <code>false</code>. 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 <code>nil</code>, it is possible to specify a default value to return.
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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
</syntaxhighlight><!--
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