Ruby Throw-Catch tutorial unclear-CodePudding

def promptAndGet(prompt)
   print prompt
   res = readline.chomp
   throw :quitRequested if res == "!"
   return res
end

catch :quitRequested do
   name = promptAndGet("Name: ")
   age = promptAndGet("Age: ")
   sex = promptAndGet("Sex: ")
   # ..
   # process information
end
promptAndGet("Name:")

From https://www.tutorialspoint.com/ruby/ruby_exceptions.htm

When executed normally, it goes through name, age, sex, and back to name again, despite the prompt only asking for the name.

Why does this happen instead of "Name" just being asked?

CodePudding user response：

That final line promptAndGet("Name") does not get immediately executed, since it's after the catch block.

The normal flow is that everything within the catch :quitRequested block gets executed immediately, in order. That's why you get all 3 prompts inside. If you answer all 3 prompts, you'll also get to the prompt on the last line.

If you answer ! to any of the three prompts, the block will terminate. So you will not get the remaining prompts inside the block.

You'll still get the prompt on the last line since it's outside of the catch.

throw is what terminates the catch block - not what initiates it.

Also, if you answer ! to that final prompt outside of the catch block, you'll get an error, because the throw was uncaught.