Ruby code beautification, split long instructions on multiple lines

问题

How can we write the following statement to improve readability?

Promotion.joins(:category).where(["lft>=? and rgt<=?", c.lft, c.rgt]).joins(:shops).where(:promotions_per_shops => { :shop_id => shops_id }).count('id', :distinct => true)

The following doesn't compile

Promotion.joins(:category)
         .where(["lft>=? and rgt<=?", c.lft, c.rgt])
         .joins(:shops)
         .where(:promotions_per_shops => { :shop_id => shops_id })
         .count('id', :distinct => true)

syntax error, unexpected '.', expecting kEND
                     .where(["lft>=? and rgt<=?", c.lft, c.rgt])

回答1:

Do it like this:

Promotion.joins(:category).
         where(["lft>=? and rgt<=?", c.lft, c.rgt]).
         joins(:shops).
         where(:promotions_per_shops => { :shop_id => shops_id }).
         count('id', :distinct => true)

回答2:

Also possible to do

Promotion.joins(:category) \
         .where(["lft>=? and rgt<=?", c.lft, c.rgt]) \
         .joins(:shops) \
         .where(:promotions_per_shops => { :shop_id => shops_id }) \
         .count('id', :distinct => true)

回答3:

It should compile in 1.9. In previous versions it was invalid indeed.

来源：https://stackoverflow.com/questions/7359948/ruby-code-beautification-split-long-instructions-on-multiple-lines