[ void ]
[void] is an an object which represents "not present" or "non-existant". This is used primarily for method return values. For example, [map->find] will return [void] when the object being searched for is not contained within the map. [void] is the default return value for a method which does not explicitly return anything. It is recommended that [void] only be used in method returns and in value comparison. To illustrate, inserting a void into a map would make it difficult to determine whether or not the value exists within the map.
[void] in Lasso has the following attributes.
- void is always equal to itself
- void is never equal to any other object type
- void always reports a size of zero
- Syntax
- Methods
- Traits
voidExamples
- Beginner
This example shows how void is used to indicate "not found" when searching a map.
Code
local(mp = map('a'=1, 'b'=2, 'c'=null))
void == #mp->find('c') // yields false. 'c' was contained within the map
#mp->find('d') == void // yields true. 'd' was not contained within the mapResult
false true
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