I am learning rails and following this thread. I am stuck with the to_proc method. I consider symbols only as alternatives to strings (they are like strings but cheaper in terms of memory). If there is anything else I am missing for symbols, then please tell me. Please explain in a simple way what to_proc means and what it is used for.
The easiest way to explain this is with some examples.
(1..3).collect(&:to_s) #=> ["1", "2", "3"]
Is the same as:
(1..3).collect {|num| num.to_s} #=> ["1", "2", "3"]
and
[1,2,3].collect(&:succ) #=> [2, 3, 4]
Is the same as:
[1,2,3].collect {|num| num.succ} #=> [2, 3, 4]
to_proc returns a Proc object which responds to the given method by symbol. So in the third case, the array [1,2,3] calls its collect method and. succ is method defined by class Integer. So this parameter is a short hand way of saying collect each element in the array and return its successor and from that create a new array which results in [2,3,4]. The symbol :succ is being converted to a Proc object so it call the Array's succ method.