Ruby apply string interpolation to a single-quote string

Question

I have a string that contains some interpolated statements, like description='Hello! I am #{self.name}'. This string is stored as-is in the database; so without the automatic string interpolation applied.

I want to apply this interpolation at a later date. I could do something crazy like eval("\"+description+\"") but there has to be a nicer, more ruby-esque way to do this, right?

In case of the eval you should trust the data. In other case it is a huge security risk. — Eugene Myasyshchev
– Eugene Myasyshchev, Commented Nov 19, 2015 at 12:14

Stefan · Accepted Answer · 2015-11-19 12:59:05Z

7

Use the % operator:

'database store string says: %{param}' % {param: 'noice'}
#=> "database store string says: noice"

edited Nov 19, 2015 at 12:59

Stefan

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answered Nov 19, 2015 at 12:12

Damiano Stoffie

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1 Comment

Stefan Over a year ago

Note that the named reference starts with %, not #

Vasu Adari · Accepted Answer · 2015-11-19 13:08:40Z

0

class Person
  attr_reader :name

  def initialize(name)
    @name = name
  end

  def description
    'Hello! I am #{self.name}'
  end

  def interpolated_description
    description.split('#').map { |v| v.match(/\{(.*)\}/) ? send($1.split('.').last) : v  }.join
  end
end

p = Person.new('Bot')

p.interpolated_description
=> "Hello! I am Bot"

How about this?

answered Nov 19, 2015 at 13:08

Vasu Adari

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