Add Return The Thing Being Printed as a Ruby TIL

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1303 TILs and counting..._
+_1304 TILs and counting..._
 
 ---
 
@@ -1095,6 +1095,7 @@ _1303 TILs and counting..._
 - [Require Entire Gemfile In Pry Session](ruby/require-entire-gemfile-in-pry-session.md)
 - [Rerun Only Failures With RSpec](ruby/rerun-only-failures-with-rspec.md)
 - [Retry A Block After An Exception](ruby/retry-a-block-after-an-exception.md)
+- [Return The Thing Being Printed](ruby/return-the-thing-being-printed.md)
 - [Returning With Sequel](ruby/returning-with-sequel.md)
 - [rexml Is A Bundled Gem As Of Ruby 3.0.0](ruby/rexml-is-a-bundled-gem-as-of-ruby-3-0-0.md)
 - [Run An Older Version Of Bundler](ruby/run-an-older-version-of-bundler.md)

ruby/return-the-thing-being-printed.md

@@ -0,0 +1,44 @@
+# Return The Thing Being Printed
+
+The [`puts`](https://ruby-doc.org/core-3.0.2/Kernel.html#method-i-puts) method
+is the canonical way of priting things to stdout in Ruby. Notably, its return
+value is always `nil`. Generally this isn't much of an issue, but can be a
+potential gotcha while debugging.
+
+Consider the following method whose behavior you are trying to investigate:
+
+```ruby
+def process(arg)
+  thing = do_something(arg)
+
+  thing.value
+end
+```
+
+I want to print out the value of thing when I execute the code to see what it
+is while debugging. So I add a `puts` statement.
+
+```ruby
+def process(arg)
+  thing = do_something(arg)
+
+  puts thing.value
+end
+```
+
+Well, I just broke the behavior of `process` because it now returns `nil`
+instead of `thing.value`.
+
+I could add an additional line that returns the correct value. Or I could use
+[`p`](https://ruby-doc.org/core-3.0.2/Kernel.html#method-i-p) which both prints
+its argument to stdout and returns it as is.
+
+```ruby
+def process(arg)
+  thing = do_something(arg)
+
+  p thing.value
+end
+```
+
+[source](https://dev.to/lofiandcode/ruby-puts-vs-print-vs-p-vs-pp-vs-awesome-5akl)