"Should I panic here?" Only if it's really broken. In Go, panics are the fire alarm — not your main error strategy.

🚨 1. So… What Is panic()?

panic() immediately stops the normal execution flow.

panic("something went terribly wrong")

Once a panic happens:

• The function exits
• All its deferred functions are run
• The panic bubbles up to the caller
• Eventually, the app crashes and prints a stack trace

func main() {
	panic("💣 Boom!")
	fmt.Println("you'll never see this")
}

⏳ 2. But What About Cleanup? → defer to the Rescue

Go runs defer statements even during a panic.

func main() {
	defer fmt.Println("cleaning up...")
	panic("something exploded")
}

Output:

cleaning up...
panic: something exploded

So yes, you can still close files, release locks, etc. even in chaos.

🧯 3. Recovering from a Panic — But Only With recover()

Use recover() inside a deferred function to catch the panic and prevent a full crash.

func safeCall() {
	defer func() {
		if r := recover(); r != nil {
			fmt.Println("Recovered:", r)
		}
	}()

        panic("unexpected error")
}

Output:

Recovered: unexpected error

✅ The program continues ❌ The error is not automatically logged, handled, or understood — you must do something with it.

👨‍🔧 4. When Should You Use Panic?

✅ Use panic() for programmer bugs, not user mistakes.

Examples:

• Corrupted internal state
• Impossible logic condition
• Invalid memory reference
• Unrecoverable system failure

❌ Don't panic when:

• A file doesn't exist
• A user sends bad input
• A network call times out

For those: use error, not panic.

🔍 5. Common Use: Crash Early in Package Init

var config = loadConfig()

func loadConfig() Config {
 data, err := os.ReadFile("config.json")
 if err != nil {
  panic("could not read config: " + err.Error())
 }
 // parse config...
}

In some cases, it's okay to crash during startup — better to fail loud than run broken.

🧠 Advanced Pattern: Wrapping Panics into Errors

You can build functions that convert panics into errors:

func safeDivide(a, b int) (result int, err error) {
	defer func() {
		if r := recover(); r != nil {
			err = fmt.Errorf("panic caught: %v", r)
		}
	}()
        if b == 0 {
            panic("division by zero")
         }
         return a / b, nil
}
res, err := safeDivide(10, 0)
fmt.Println("err:", err) // err: panic caught: division by zero

Useful in libraries and tools where robustness matters more than purity.

⚖️ 6. Panic vs Error Quick Table

| Case                                | Use `error`  | Use `panic()`               |
| ----------------------------------- | -----------  | --------------------------- |
| Invalid user input                  | ✅           | ❌                          |
| Missing config file                 | ✅           | Maybe (if fatal)            |
| Internal bug (should never happen)  | ❌           | ✅                          |
| Network failure                     | ✅           | ❌                          |
| Corrupted memory / data             | ❌           | ✅                          |
| Logic error like index out of range | ❌           | ✅ (Go panics automatically)|

🧹 7. Graceful Shutdowns Using defer + recover

func main() {
	defer func() {
		if r := recover(); r != nil {
			log.Println("Something broke:", r)
			// Maybe: restart app, alert system, clean exit
		}
	}()
        runApp()
}

You'll often see this pattern in:

• HTTP servers
• Goroutines
• Workers/daemons

It's defensive programming — you stay alive even when something explodes.

🚫 But Don't Overuse It

• Panic is not Go's exception system.
• It should never replace error handling.
• If you panic too much, you lose the clarity Go is known for.

Go's simplicity depends on manual, visible control flow — not hidden stack jumping.

✅ Summary

Go gives you panic/recover — but trusts you to use it wisely. It's the emergency brake, not the steering wheel.

In real-world Go:

• You return errors for expected failures.
• You panic when something's broken at the core.

Keep your crashes intentional, controlled, and rare. 🚀