Is it possible to use `retry` keyword inline with `if`?

Question

I have to surround everything with begin-rescue-end block. I've written code that looks like:

begin
  bet = Dialogs.enter_your_bet
  approx.calculate_average_profit(bet)
  approx.print_profits_table
  retry if Dialogs.play_again?
rescue;retry
end

The line retry if Dialogs.play_again? caused the following error:

./main:14: Invalid retry
./main: compile error (SyntaxError)

Is it possible to make this kind of inline retry to work with if clause without regular if-end multiline approach?

`rescue` is used to handle exceptions. Don't use exceptions for control flow. — Stefan, Dec 02 '15 at 10:09
Do you want to `retry` in case of an exception. Or do you want to re-run the block if the condition is met? You might want to use a `while` block in the second case... — spickermann, Dec 02 '15 at 10:11

score 5 · Answer 1 · answered Dec 02 '15 at 09:57

5

retry works in rescue blocks (or in iterators). And it works with if. Try this:

begin
  bet = Dialogs.enter_your_bet
  approx.calculate_average_profit(bet)
  approx.print_profits_table
rescue
  retry if Dialogs.play_again?
end

answered Dec 02 '15 at 09:57

spickermann

100,941
9
101
131

The `rescue` block is only called if an exception is raised. – Stefan Dec 02 '15 at 10:02
@Stefan yes, you're right. And that's why this implementation is not what I want (my mistake, maybe I should explain what I need more clearly). I selfanswered this question with a possible workaround to make things work. – ddnomad Dec 02 '15 at 10:13

score 1 · Accepted Answer · answered Dec 02 '15 at 10:11

1

Ok, thank you all for answers! I understood what was a problem, but your workarounds wasn't what I need. Actually, rescue part was for restarting input prompt in case of illegal input from a user, while my 'retry' inside begin was to restart block from another user input (y/n question).

So after some investigation, this code would work flawlessly:

begin
  loop do
    bet = Dialogs.enter_your_bet(gapes[0],gapes[1])
    approx.calculate_average_profit(bet)
    approx.print_profits_table
  break if !Dialogs.play_again?
  end
rescue;retry
end

And again, thanks for been so awesomely active community. Take care!

answered Dec 02 '15 at 10:11

ddnomad

373
3
15

`if !Dialogs.play_again?` is equivalent to `unless Dialogs.play_again?` – Stefan Dec 02 '15 at 10:11
@Stefan yes, surly. Yet I have a terrible headache using 'unless' keyword, so I got rid of it :) – ddnomad Dec 02 '15 at 10:14
Note that you are `retry`-ing the whole `loop` in case of an exception. I would wrap the `loop`'s body in a `begin-rescue-end` block and remove the `retry`. – Stefan Dec 02 '15 at 10:22
@Stefan in my particular case it's ok, as I store all the necessary info in approx object instance that was created before. But again - thanks for an observation. – ddnomad Dec 02 '15 at 10:27

steenslag · Answer 3 · 2015-12-02T10:42:29.813

0

redo is used for control flow.

Quoting the docs: "In Ruby 1.8 you could also use retry where you used redo. This is no longer true, now you will receive a SyntaxError when you use retry outside of a rescue block. See Exceptions for proper usage of retry."

edited Dec 02 '15 at 10:42

answered Dec 02 '15 at 10:31

steenslag

79,051
16
138
171

There's no way to exit the loop. – Stefan Dec 02 '15 at 10:33

Is it possible to use `retry` keyword inline with `if`?

3 Answers3