Another way to write: if some_variable && some_valiable.size == 2

In Ruby & in RoR I oft find myself testing whether an object exists, then whether an object's properties match some criteria. Like so:

if params[:id] && params[:id].size == 40
  ...do stuff
end

Is there a more efficient way to do this? Something like:

if params[:id]开发者_运维百科.size == 40 rescue false

but without using the rescue?

With Rails 2.3 you can use Object#try method:

if params[:id].try(:size) == 40
  # do stuff
end

try will return nil when called on nil (with any arguments). Hope that makes sense.

You can do it witout additional gems.

if params[:id].to_a.size == 40
    ... do stuff
end

Try the andand gem:

require 'andand'

if params.andand.size == 40
  ...do stuff
end