What is retry in Ruby: Explanation and Example

retry in Ruby is a keyword used inside a begin-rescue block to restart the code from the beginning of the begin block after an error occurs. It helps retry an operation that failed, like trying again after a temporary problem.

How It Works

Imagine you are trying to do something that might fail, like sending a letter. If the post office is closed, you want to try again later. In Ruby, retry lets you do this by restarting the code inside a begin block after an error happens.

When Ruby encounters an error inside a begin block, it jumps to the rescue part to handle the error. If you use retry inside rescue, Ruby goes back to the start of the begin block and tries the code again. This repeats until the code runs without error or the program stops.

Example

This example shows how retry can try to open a file multiple times if it fails the first time.

ruby

attempts = 0
begin
  attempts += 1
  puts "Trying to open file, attempt #{attempts}"
  # Simulate failure for first 2 attempts
  raise "File not found" if attempts < 3
  puts "File opened successfully"
rescue
  puts "Failed to open file, retrying..."
  retry
end

Output

Trying to open file, attempt 1
Failed to open file, retrying...
Trying to open file, attempt 2
Failed to open file, retrying...
Trying to open file, attempt 3
File opened successfully

When to Use

Use retry when you want to automatically try an operation again after it fails due to a temporary problem. For example, retrying a network request if the connection drops or trying to read a file that might be temporarily locked.

Be careful to avoid infinite loops by limiting retries or adding delays between attempts.

Key Points

• retry restarts the begin block after an error.
• It is used inside rescue to handle exceptions by trying again.
• Useful for temporary failures like network or file access issues.
• Always control retry attempts to prevent endless loops.

Key Takeaways

retry restarts the code inside a begin block after an error.

It is used inside rescue to handle exceptions by retrying the operation.

Ideal for temporary failures like network or file access problems.

Always limit retries to avoid infinite loops or crashes.