Ruby check if nil before calling method

Question

I have a string in Ruby on which I\'m calling the strip method to remove the leading and trailing whitespace. e.g.

s = \"12345 \"
s.strip

H

Answer 1

I'd opt for a solution where s can never be nil to start with.

You can use the || operator to pass a default value if some_method returns a falsy value:

s = some_method || '' # default to an empty string on falsy return value
s.strip

Or if s is already assigned you can use ||= which does the same thing:

s ||= '' # set s to an empty string if s is falsy
s.strip

Providing default scenario's for the absence of a parameters or variables is a good way to keep your code clean, because you don't have to mix logic with variable checking.

Answer 2

If you don't mind the extra object being created, either of these work:

"#{s}".strip
s.to_s.strip

Without extra object:

s && s.strip
s.strip if s

Answer 3

I guess the easiest method would be the following:

s.strip if s

Answer 4

If you want to avoid the error that appears in the question:

s.to_s.strip

Answer 5

You can use method try from ActiveSupport (Rails library)

gem install activesupport

require 'active_support/core_ext/object/try'
s.try(:strip)

or you can use my gem tryit which gives extra facilities:

gem install tryit

s.try { strip }

Answer 6

Simply put:

s = s.nil? ? s : s.strip

Tl;dr Check if s is nil, then return s, otherwise, strip it.