Exceptional Ruby: Master the Art of Handling Failure in Ruby by Avdi Grimm

exceptional_ruby_book_quiz.rb

Great book! Here are my quiz notes:

- What is the diff bt raise and fail?
=> no diff

- Are raise//fail ruby keywords or methods?
=> Kernel#raise (are methods)

- Re-raise last exception
=>
# With no arguments will re-raise exception in $! If nil then RuntimeError
# note $! value is nil initialized as soon as the begin..rescue.end block terminates
raise

- What is the third argument of raise and give an example of what to put there.
=> the backtrace, use for example Kernel#caller

- What is catch/throw used for?
=> not related to exceptions, catch/throw allows you 
to quickly exit blocks back to a point where a catch is defined for a specific symbol

- Diffs bt `redo` vs `retry`
=> Both ruby keywords are used to re-execute parts of a loop but:
redo only repeats the current iteration
retry repeats the whole loop from the start in 1.8 but in 1.9 gives SyntaxError: Invalid retry
Note retry should only be used inside immediate rescue blocks

- What can you use to ignore/continue/retry//etc on every ruby program error, console based?
=> the `hammertime` gem. just require 'hammertime'

- Test unit, describe the test helpers (assertions) for
equality, check nothing raised, check something raised.
=>
assert_equal val1, val2
assert_nothing_raised { block }
# ensure some exception is not raised
assert_nothing_raised ArgumentError { block }
# ensure something is raised
assert_raise { block }
# ensure some exception is raised
assert_raise NameError { puts asd }

- What's caller() method used for, where's defined and what param takes?
=>
Kernel#caller(omit_from_start=1)
# Returns the current execution stack.
# An array containing strings in the form “file:line” or “file:line: in `method'”
# Has an optional start parameter with the number of initial stack entries to omit from the result.
# when omit=0 it will also show the current file:line:method where caller() was called