A dozen readings later...

I guess I am finally reaching the "advanced" Rails tricks, since I just used this. (Although, I have to admit the origin was a ryanb tutorial on editing multiple models, not from repeated readings...)

from Agile Web Development with Rails

An Extension to Ruby Symbols

(This section describes an advanced feature of Ruby and can be safely skipped on the first dozen or so readings....)

We often use iterators where all the block does is invoke a method on its argument. We did this in our earlier group_by and index_by examples.

groups = posts.group_by {|post| post.author_id}

Rails has a shorthand notation for this. We could have written this code as

groups = posts.group_by(&:author_id)