Why defer is used in Go - Quick Recap

Recall & Review

beginner

What does the defer keyword do in Go?

The defer keyword schedules a function call to run after the current function finishes, no matter how it exits.

beginner

Why is defer useful for resource management?

defer helps ensure resources like files or locks are released properly, even if the function returns early or an error occurs.

intermediate

When are deferred functions executed in Go?

Deferred functions run right before the surrounding function returns, in last-in-first-out order.

intermediate

How does defer improve code readability?

It keeps cleanup code close to resource allocation, making it easier to read and maintain.

intermediate

Can multiple defer statements be used in one function?

Yes, and they execute in reverse order of their appearance when the function returns.

What happens when you use defer in a Go function?

A The deferred function runs before the surrounding function starts

B The deferred function runs immediately

C The deferred function runs after the surrounding function finishes

D The deferred function never runs

Deferred functions run after the surrounding function finishes, ensuring cleanup happens last.

Why is defer helpful when working with files?

A It opens files faster

B It reads files asynchronously

C It prevents files from opening

D It automatically closes files when the function ends

Using defer to close files ensures they are closed properly even if errors occur.

In what order do multiple deferred functions execute?

A In reverse order of deferral

B They execute simultaneously

C Random order

D In the order they were deferred

Deferred functions execute in last-in-first-out order, so the last deferred runs first.

Which of these is NOT a reason to use defer?

A To improve code readability

B To speed up program execution

C To ensure cleanup code runs

D To handle early returns safely

defer does not speed up execution; it helps with cleanup and readability.

When exactly does a deferred function run?

A Before the function returns

B After the function returns

C At the start of the function

D Only if the function panics

Deferred functions run just before the function returns, regardless of how it returns.

Explain in your own words why defer is useful in Go programs.

Think about what happens when you open a file or lock a resource.

Describe the order in which multiple deferred functions execute and why this order matters.

Imagine stacking plates and removing them one by one.