Rails 4: how to use string interpolation into Ruby regex in model helper

Question

In my Rails 4 app, I have the following post helper:

def link_highlight(string)
  init1 = string
  result1 = string.to_s.gsub!(/((https|http)?:\/\/[\S]+)/, '<span class="highlight">\1</span>')
  if result1.nil?
    init1
  else
    result1
  end
end

I use it to style links in the post.copy string, thanks to the highlight class.

Now, I would like to pass a second argument to the method, so that I can apply different styles to the links, thanks to different highlight classes:

def link_highlight(string, color)
  init1 = string
  result1 = string.to_s.gsub!(/((https|http)?:\/\/[\S]+)/, '<span class="highlight-color">\1</span>')
  if result1.nil?
    init1
  else
    result1
  end
end

When I do that, the class applied to the links in the string is actually highlight-color.

Instead, I would like to link_highlight(string, blue) to apply the highlight-blue class to the string.

—————

UPDATE: I tried the solution offered by @dankohn but it is actually not working.

If I do:

def link_highlight(string, color)
  init1 = string
  result1 = string.to_s.gsub!(/((https|http)?:\/\/[\S]+)/, '<span class="highlight-#{color}">\1</span>')
  if result1.nil?
    init1
  else
    result1
  end
end 

Then I get:

undefined local variable or method `color' for #<#<Class:0x007f911de61698>:0x007f911995f518>

So, I also tried to run:

in my view, but then I get back to the initial problem and get:

#{"color"}">

displayed instead of the value of color.

—————

How can I replace color by its value? Can I use string interpolation?

Answer 1

Try: "<span class=\"highlight-#{color}\">\1</span>"