Ruby Language Catching Exceptions with Begin / Rescue Code That Should Always Run
Example
Use an ensure clause if there is code you always want to execute.
def divide(x, y)
begin
z = x/y
return z
rescue ZeroDivisionError
puts "Don't divide by zero!"
rescue TypeError
puts "Division only works on numbers!"
return nil
rescue => e
puts "Don't do that (%s)" % [e.class]
return nil
ensure
puts "This code ALWAYS runs."
end
end
The ensure clause will be executed when there is an error:
> divide(10, 0)
Don't divide by zero! # rescue clause
This code ALWAYS runs. # ensure clause
=> nil
And when there is no error:
> divide(10, 2)
This code ALWAYS runs. # ensure clause
=> 5
The ensure clause is useful when you want to make sure, for instance, that files are closed.
Note that, unlike the else clause, the ensure clause is executed before the begin or rescue clause returns a value. If the ensure clause has a return that will override the return value of any other clause!
