Quick index
print vs puts
First thing to notice, they print the content, but both return nil.
puts
- Appends a new line at the end of the return
- Attempts to convert everything into a string by calling the
to_smethod
irb(main):002:0> puts "take a look at where the cursor is :) "
take a look at where the cursor is :)
=> nil
irb(main):004:0> 2.times {puts "hey you!"}
hey you!
hey you!
=> 2
# Puts converts everything it cans to string
irb(main):031:0> puts [1,nil,nil,2]
1
2
=> nill
- no new lines appended here
irb(main):001:0> print "you should not see a new line at the end"
you should not see a new line at the end => nil
irb(main):003:0> 2.times {print "hey you!"}
hey you!hey you! => 2
print [1,nil,nil,2]
[1, nil, nil, 2] => nil
p vs pp vs ap
It is more useful for debugging as it will show ( return ) a raw version of the object.
They are similar to puts as it adds a newline at the end, but instead of calling to_s:
p
- calls the
inspectmethod.
irb(main):033:0> p 1
1
=> 1
irb(main):034:0> p '1'
"1"
=> "1"
irb(main):035:0>
irb(main):035:0> puts 1
1
=> nil
irb(main):036:0> puts '1'
1
=> nil
irb(main):037:0> puts '1'.inspect
"1"
=> nil
pp
- calls the
pretty_inspectmethod. More useful when dealing with complex nested objects.
irb(main):038:0> data = [ false, 42, %w(forty two), { :now => Time.now, :class =
> Time.now.class, :distance => 42e42 } ]
=>
[false,
...
irb(main):039:0> pp data
[false,
42,
["forty", "two"],
{:now=>2022-06-09 12:06:44.161486 -0400, :class=>Time, :distance=>4.2e+43}]
=>
[false,
42,
["forty", "two"],
{:now=>2022-06-09 12:06:44.161486 -0400, :class=>Time, :distance=>4.2e+43}]
irb(main):040:0>
ap
- Most recently version of Ruby does not contain
ap[at the time of writing this article, ruby 3.1.2], you will have to install it by running:
gem install awesome_print
and will have to add require "awesome_print" into your irb session.
irb(main):002:0> require "awesome_print"
=> true
irb(main):003:0> data = [ false, 42, %w(forty two), { :now => Time.now, :class =
> Time.now.class, :distance => 42e42 } ]
=>
[false,
...
irb(main):004:0> ap data
[
[0] false,
[1] 42,
[2] [
[0] "forty",
[1] "two"
],
[3] {
:now => 2022-06-09 12:56:59.184906 -0400,
:class => Time < Object,
:distance => 4.2e+43
}
]
=> nil
How they actually work
They all use the $stdout global variable. It represents the current standard output.
Those methods we have talked about today, communicate with the output stream on your computer (which will communicate with the Operating System) by sending the message using the $stdout global variable, and output the message to the console.
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