.gitattributes

*.rb  diff=ruby

.gitconfig

[core]
  attributesfile = ~/.gitattributes

git_attributes.md

Git supports an attributes file. A good read is https://git-scm.com/docs/gitattributes

Among the cool features is the ability to show ruby method definitions in the diffs.

The default behavior for ruby is to show the Class

Before

diff --git a/tmp/rubya.rb b/tmp/rubyb.rb
index 554bf890..fa453b1d 100644
--- a/tmp/rubya.rb
+++ b/tmp/rubyb.rb
@@ -8,6 +8,6 @@ class Foo
     # more context
     # more context

-    3
+    4
   end
 end

Add a .gitattributes file

After

diff --git a/tmp/rubya.rb b/tmp/rubyb.rb
index 554bf890..fa453b1d 100644
--- a/tmp/rubya.rb
+++ b/tmp/rubyb.rb
@@ -8,6 +8,6 @@ def my_foo
     # more context
     # more context

-    3
+    4
   end
 end

I personally set a global .gitattributes using ~/.gitconfig

rubya.rb

class Foo
  # lots of context
  # lots of context
  # lots of context

  def my_foo
    # more context
    # more context
    # more context

    3
  end
end