one?(*args) public

Passes each element of the collection to the given block. The method returns true if the block returns true exactly once. If the block is not given, one? will return true only if exactly one of the collection members is true.

If instead a pattern is supplied, the method returns whether pattern === element for exactly one collection member.

%w{ant bear cat}.one? { |word| word.length == 4 }  #=> true
%w{ant bear cat}.one? { |word| word.length > 4 }   #=> false
%w{ant bear cat}.one? { |word| word.length < 4 }   #=> false
%w{ant bear cat}.one?(/t/)                         #=> false
[ nil, true, 99 ].one?                             #=> false
[ nil, true, false ].one?                          #=> true
[ nil, true, 99 ].one?(Integer)                    #=> true
[].one?                                            #=> false
Show source
Register or log in to add new notes.