Ruby automatically calls to_s method when object is created

Question

``` class A def initialize(string, number) @string = string @number = number end def to_s "In to_s:
 #{@string}, #{@number}
" end def to_a "In to_a:
 #{@string}, #{@number}
" end end puts a = A.new("hello world", 5) ``` output is ``` In to_s: hello world, 5 ``` How is the `to_s` method called automatically? Why isn't another method called automatically such as `to_a`? Since I did not write puts in the `to_s` method, why is output printed.

Accepted Answer

You're sending it to `puts`, which will try to render the object as a string using `to_s`.

If you changed your last line to: `puts A.new("hello world", 5).to_a`, it would instead call `to_s` on the returned Array and A's `to_s` would not be called.

Ruby automatically calls to_s method when object is created

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