rails/rails — pull request #7918 by ayrton (2012-10-12 08:52:50+00:00)
Title: Undefined ivars return nil by default

When calling an undefined ivar, it returns nil by default, however it does not create the ivar, thus there shouldn't be a performance penalty by this change, however it does improve readability imo.

``` Ruby
if defined?(@expires_in) && defined?(@created_at) && @expires_in && @created_at`
```

vs.

``` Ruby
if @expires_in && @created_at`
```
What do you think?