How to Embed Regular Expressions in Other Regular Expressions in Ruby

How to combine these two Ruby string tests in one regular expression?

The most important improvement you can make is to also test that the word and the parentheseses have the correct relationship. If I understand correctly, "link(url link_name)" should be a match but "(url link_name)link" or "link stuff (url link_name)" should not. So match "link", the parentheses, and their contents, and capture the contents, all at once:

"stuff link(url link_name) more stuff".match(/link\((\S+?) (\S+?)\)/)&.captures
=> ["url", "link_name"]

(&. is Ruby 2.3; use Rails' .try :captures in older versions.)

Side note: string.scan(regex).present? is more concisely written as string =~ regex.

Ruby regular expression using variable name

The code you think doesn't work, does:

var = "Value"
str = "a test Value"
p str.gsub( /#{var}/, 'foo' )   # => "a test foo"

Things get more interesting if var can contain regular expression meta-characters. If it does and you want those matacharacters to do what they usually do in a regular expression, then the same gsub will work:

var = "Value|a|test"
str = "a test Value"
str.gsub( /#{var}/, 'foo' ) # => "foo foo foo"

However, if your search string contains metacharacters and you do not want them interpreted as metacharacters, then use Regexp.escape like this:

var = "*This*"
str = "*This* is a string"
p str.gsub( /#{Regexp.escape(var)}/, 'foo' )
# => "foo is a string"

Or just give gsub a string instead of a regular expression. In MRI >= 1.8.7, gsub will treat a string replacement argument as a plain string, not a regular expression:

var = "*This*"
str = "*This* is a string"
p str.gsub(var, 'foo' ) # => "foo is a string"

(It used to be that a string replacement argument to gsub was automatically converted to a regular expression. I know it was that way in 1.6. I don't recall which version introduced the change).

As noted in other answers, you can use Regexp.new as an alternative to interpolation:

var = "*This*"
str = "*This* is a string"
p str.gsub(Regexp.new(Regexp.escape(var)), 'foo' )
# => "foo is a string"

Regular expressions in Ruby with special characters

if you already know you're always splitting on the same character, you can just provide the character as a string:

   > "John Doe+123456".split('+')  # no regular expression needed
   => ["John Doe", "123456"]

or if you have to use a regular expression, then escape the + with a \ :

   > "John Doe+123456".split(/\+/) # using a regular expression; escape the +
   => ["John Doe", "123456"]

last not least, here is another way to do this:

   > "John Doe+123456".scan(/[^+]+/) # find all sequences of characters which are not a +
   => ["John Doe", "123456"]

Can I have an Array of regular expressions in ruby?

Can I have an Array of regular expressions in ruby?

Yes.

If there is a more sophisticated way [to test that a given string matches all regex]?

Use Enumerable#all?.

patterns = [/foo/, /bar/]
input = 'baz'
patterns.all? { |pattern| pattern.match?(input) }

match? was added recently, in ruby 2.4.

inserting variable value in regex in ruby script

First of all, regxPlayerVariable is not a Regexp, it's a String. And the reason why your interpolation does not work is because you are using single quotes. Look:

foo = "bar"
puts '#{foo}'   # => #{foo}
puts "#{foo}"   # => bar
puts %q{#{foo}} # => #{foo}
puts %Q{#{foo}} # => bar
puts %{#{foo}}  # => bar
puts /#{foo}/   # => (?-mix:bar)
puts %r{#{foo}} # => (?-mix:bar)

Only the last two are actually regular expressions, but here you can see which quoting expressions do interpolation, and which don't.

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