Ruby rescue vs try vs ternary | Ruby exception handling

All of us have faced this situation when, the current_resource object provided by devise turns out to be nil. All method invocations on current_resource on current_resource will throw an undefined method for nil:NilClass exception.

To handle this, we can try one of the following.

1. current_resource.name rescue nil
2. current_resource.try(:name)
3. current_resource ? current_resource.name : nil

But, what is the most efficient way? Let's find out.

require 'benchmark'

n = 5000000
current_resource = nil

Benchmark.bm do |x|
  x.report("rescue") do n.times { current_resource.name rescue nil } end
  x.report("try") do n.times { current_resource.try(:name) } end
  x.report("ternary") do n.times { current_resource ? current_resource.name : nil } end
end


user       system        total         real
--------------------------------------------------------------
rescue   | 16.300000   | 0.600000  | 16.900000 | (16.910213)
try      | 0.7800000   | 0.000000  | 0.7800000 | ( 0.783828)
ternary  | 0.2800000   | 0.000000  | 0.2800000 | ( 0.277966)

Note that rescue is considerably inefficient compared to the other two (almost 60 times). The Ternary operator seems to be the most sound option.

Written by

Nithin Krishna

Published at

Jul 15, 2014

Posted in

Research and Articles

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