Is there equivalent for PHP's print_r in Ruby / Rails?

Question

In PHP you can do:

print_r($var) or vardump($var)

which prints \"human-readible\" information about variable.

Is there equ

Answer 1

One approach I lean on a lot is this:

logger.debug "OBJECT: #{an_object.to_yaml}"

Easy to read, although it can get a little unwieldy for large objects.

Answer 2

In Rails templates you can do

<%= debug an_object %>

and it will do nice HTML PRE output.

Answer 3

Instead of requiring 'pp' and using pp, you can simply do

p object

Tested example

require 'pp'

class A
  def initialize
    @a = 'somevar'
    @b = [1,2,3]
    @c = {'var' => 'val'}
  end
end

a = A.new
pp a # Gives -> #<A:0x2c6d048 @a="somevar", @b=[1, 2, 3], @c={"var"=>"val"}>
p a # Gives -> #<A:0x2c6d048 @a="somevar", @b=[1, 2, 3], @c={"var"=>"val"}>. No need to require 'pp'

Answer 4

Try using pp. You will need to require it in scripts (or in irb if your .irbc doesn't already do this):

require 'pp'

Then you can 'PrettyPrint' an object thus:

pp object

Answer 5

Check out the guide for debugging rails: http://guides.rubyonrails.com/debugging_rails_applications.html

hints: script/console is great to try stuff in the context of your app script/server --debugger to start the server with a debugger turned on, you can then use 'debug' in your code to break into an interactive shell

Answer 6

I know this is an old post, but it is the first thing that Google pops up when searching for "Ruby equivalent of PHP print_r". I'm using Ruby in the command line mode, and there's really not a very good equivalent. "pp" is ok for fairly simple structures, but as soon as you start nesting hashes in arrays in hashes in more arrays, it turns into a jumble pretty fast. Since I haven't found a good emulation of print_r, I wrote one myself. It's good enough for my purposes, not overly complicated and I thought I'd share it to save other people some headache. Compare the output with the real PHP print_r

def print_r(inHash, *indent)
    @indent = indent.join
    if (inHash.class.to_s == "Hash") then
        print "Hash\n#{@indent}(\n"
        inHash.each { |key, value|
            if (value.class.to_s =~ /Hash/) || (value.class.to_s =~ /Array/) then
                print "#{@indent}    [#{key}] => "
                self.print_r(value, "#{@indent}        ")
            else
                puts "#{@indent}    [#{key}] => #{value}"
            end
        }
        puts "#{@indent})\n"
    elsif (inHash.class.to_s == "Array") then
        print "Array\n#{@indent}(\n"
        inHash.each_with_index { |value,index|
            if (value.class.to_s == "Hash") || (value.class.to_s == "Array") then
                print "#{@indent}    [#{index}] => "
                self.print_r(value, "#{@indent}        ")
            else
                puts "#{@indent}    [#{index}] => #{value}"
            end
        }
        puts "#{@indent})\n"
    end
    #   Pop last indent off
    8.times {@indent.chop!}
end

Here's an example (made messy on purpose to show why the PHP print_r is so nice):

    carTools =  [ "Socket Set", "Combination Wrenches", "Oil Filter puller", "Brake Compressor" ]
    houseTools =[ "Circular Saw", "Miter Saw", "Drill" ]
    garageItems = Hash["Car1" => "Ford Mustang", "Car2" => "Honda Civic", "Bike1" => "IronHorse"]
    garageItems["Tools"] = Hash["Car Tools" => carTools, "House Tools" => houseTools]
    constructionSupplies = Hash["Plywood" => ["3/4\" T&G Plywood Sheets", "1/2\" Plywood Sheets"],
                                "Boards" => ["2x4s", "2x6s", "Engineered I-Joists"],
                                "Drywall" => ["4x8 1/2\" Sheetrock", "Mesh tape", "Paper tape", "Joint compount"]]
    carParts = Hash["Mustang" => ["Clutch", "Transmission", "3.55 Ring & Pinion Gears", "Differential", "30# Injectors", "Pro-M 77mm MAF"]]
    garageItems["Supplies"] = ["Oil", "WD40", constructionSupplies, carParts, "Brake Fluid"]
    print_r(garageItems)

Output of print_r (actually comprehensible by a human):

    Hash
    (
        [Car1] => Ford Mustang
        [Car2] => Honda Civic
        [Bike1] => IronHorse
        [Tools] => Hash
            (
                [Car Tools] => Array
                    (
                        [0] => Socket Set
                        [1] => Combination Wrenches
                        [2] => Oil Filter puller
                        [3] => Brake Compressor
                    )
                [House Tools] => Array
                    (
                        [0] => Circular Saw
                        [1] => Miter Saw
                        [2] => Drill
                    )
            )
        [Supplies] => Array
            (
                [0] => Oil
                [1] => WD40
                [2] => Hash
                    (
                        [Plywood] => Array
                            (
                                [0] => 3/4" T&G Plywood Sheets
                                [1] => 1/2" Plywood Sheets
                            )
                        [Boards] => Array
                            (
                                [0] => 2x4s
                                [1] => 2x6s
                                [2] => Engineered I-Joists
                            )
                        [Drywall] => Array
                            (
                                [0] => 4x8 1/2" Sheetrock
                                [1] => Mesh tape
                                [2] => Paper tape
                                [3] => Joint compount
                            )
                    )
                [3] => Hash
                    (
                        [Mustang] => Array
                            (
                                [0] => Clutch
                                [1] => Transmission
                                [2] => 3.55 Ring & Pinion Gears
                                [3] => Differential
                                [4] => 30# Injectors
                                [5] => Pro-M 77mm MAF
                            )
                    )
                [4] => Brake Fluid
            )
    )