How can I use a regex match as a hash index in Ruby? -

i'm new ruby , i've run issue can't solve.

i'm trying use gsub() match pattern in string, use match index hash. far, haven't been able figure out. here's code:

farm = { "pig_num" => 5, "horse_num" => 2, "cow_num" => 4} assessment = "there 'pig_num' pigs on farm"  assessment.gsub(/'(.+?)'/, '\1') # => "there pig_num pigs on farm" assessment.gsub(/'(.+?)'/, farm) # =>  "there  pigs on farm" assessment.gsub(/'(.+?)'/, farm['\1']) # => typeerror: no implicit conversion of nil string assessment.gsub(/'(.+?)'/) { |key| farm[key] } 

the first call gsub() shows matching string want.

the second call attempt use gsub(pattern, hash) flavor found @ the ruby documentation site.

the third call trying reference value using match index.

the fourth fancy pants way thought might work using lambda/proc/block.

what doing wrong?

try this

assessment.gsub(/#{farm.keys.join('|')}/, farm)