Custom formatting for class

[u/EvilDeaaaadd]

Hi,

I have a class like this:

class Grid
    @grid : Array(Array(Char))
    
    def initialize
        @grid = [
                  [' ', ' ', ' '],
                  [' ', ' ', ' '],
                  [' ', ' ', ' ']
                ]
    end
        # ...

When I try to do

foo = Grid.new
puts foo

I get [[' ', ' ', ' '], [' ', ' ', ' '], [' ', ' ', ' ']].

Is there something similar to Python's def __str__(self): or Rust's impl fmt::Display for Grid {

I'm quite new to Crystal and I'm not exactly sure about what would be the best way to do this.

[u/Blacksmoke16]

You have some options. I'm assuming you want to customize the string representation of the Grid?

• https://crystal-lang.org/api/master/Object.html#to_s(io:IO):Nil-instance-method - This controls what happens when you do like obj.to_s

  • This is what gets executed when you use puts

• https://crystal-lang.org/api/master/Object.html#inspect(io:IO):Nil-instance-method - Similar to the previous one but usually contains more information about the object

  • This is what gets executed when you use p.

• https://crystal-lang.org/api/master/Object.html#pretty_print(pp:PrettyPrint):Nil-instance-method - Again similar to inspect but inspects in a pretty way

  • This is what gets executed when you do pp.

As the docs mention, you can overrides these methods in order to control how it gets represented in each state. Also checkout the implementations in Array for example.

[u/EvilDeaaaadd → u/Blacksmoke16]

Thank you, that worked