Ruby Language Gem Usage Checking if a required gem is installed from within code
Example
To check if a required gem is installed, from within your code, you can use the following (using nokogiri as an example):
begin
found_gem = Gem::Specification.find_by_name('nokogiri')
require 'nokogiri'
....
<the rest of your code>
rescue Gem::LoadError
end
However, this can be further extended to a function that can be used in setting up functionality within your code.
def gem_installed?(gem_name)
found_gem = false
begin
found_gem = Gem::Specification.find_by_name(gem_name)
rescue Gem::LoadError
return false
else
return true
end
end
Now you can check if the required gem is installed, and print an error message.
if gem_installed?('nokogiri')
require 'nokogiri'
else
printf "nokogiri gem required\n"
exit 1
end
or
if gem_installed?('nokogiri')
require 'nokogiri'
else
require 'REXML'
end
