How can I ignore first results from a function in Lua?
Lua functions can return multiple results :
a, b, c = unpack({'one', 'two', 'three'})
If I'm not interested in the third return value, I can choose to ignore it when calling the function :
a, b = unpack({'one', 'two', 'three'})
Is there a similar way to ignore the X first elements when calling the function ?
开发者_如何学编程I could write this code if I only want the third return value, but I was wondering if a cleaner code exists :
_, _, c = unpack({'one', 'two', 'three'})
You can use the select
function. It will return all arguments after index
, where index
is the first argument given to select
.
Examples:
c = select(3, unpack({'one', 'two', 'three'}))
b, c = select(2, unpack({'one', 'two', 'three'}))
b = select(2, unpack({'one', 'two', 'three'})) --discard last return value
That said, I think in most cases, writing _,_,c = f()
is cleaner. select
is mostly useful when the argument number is not known in advance, or when chaining function calls together (e.g. f(select(2, g()))
)
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