Exceptions

Question 1

How to add and handle exceptions?

Answer 1

begin
  raise 'hey'
rescue
  p 'Error was handled'
end

Question 2

How to handle and show an error message?

Answer 2

begin
  raise 'hey'
rescue => error
  p error.message
end

Question 3

How to add and handle an error with a specific class?

Answer 3

begin
  raise ArgumentError, 'hey'
rescue ArgumentError => error
  p error.message
end

Question 4

How to create your own error class?

Answer 4

class MyError < StandardError
end

begin
  raise MyError, 'hey'
rescue MyError => error
  p error.message
end

Question 5

How to handle several exceptions with different types?

Answer 5

begin
  raise StandardError, 'hey'
rescue ArgumentError => error
  p error.message
rescue StandardError => error
  p error.message
end

Question 6

How to rerun code with the exception one more time?

Answer 6

# use retry
value = true
begin
  raise 'hey' if value
  p 'works'
rescue
  p 'Try one more time'
  value = false
  retry
end

Question 7

How to add part of code which should be run every time?

Answer 7

ensure

begin
  raise 'hey'
rescue
  p 'rescue code'
ensure
  p 'ensure code'
end

Question 8

What is throw and catch exception? How to use it?

Answer 8

# tryes to "catch" something that was "throw"
# catch
and throw work with symbols rather than exceptions.

catch(:finish) do
  1000.times do
     x = rand(1000)
    throw :finish if x == 123
   end
    puts "Generated 1000 random numbers without generating 123!"
end