v::noWhitespace()
Validates if a string contains no whitespace (spaces, tabs and line breaks);
v::noWhitespace()->validate('foo bar'); //false
v::noWhitespace()->validate("foo\nbar"); //false
Like other rules the input is still optional.
v::string()->noWhitespace()->validate(''); //true
v::string()->noWhitespace()->validate(' '); //false
This is most useful when chaining with other validators such as v::alnum()