document `try!` in ActiveSupport core ext guide

https://twitter.com/avdi/status/660141673993777156

1 files changed, 7 insertions, 0 deletions

diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 556b5ede3c..f6fc255c24 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -248,6 +248,13 @@ end
 @person.try { |p| "#{p.first_name} #{p.last_name}" }
 ```
 
+Note that `try` will swallow no-method errors, returning nil instead. If you want to protect against typos, use `try!` instead:
+
+```ruby
+@number.try(:nest)  # => nil
+@number.try!(:nest) # NoMethodError: undefined method `nest' for 1:Fixnum
+```
+
 NOTE: Defined in `active_support/core_ext/object/try.rb`.
 
 ### `class_eval(*args, &block)`