What is the purpose of using the defer construct in Go?

The defer construct is used for deferred execution of a function or method. The scheduled function will be executed immediately before the surrounding function returns.

Main purposes of using defer:

• Resource release: Guaranteed closing of files, cleaning up network connections, releasing mutex locks and other system resources, even if a panic occurs in the code.
• Code simplification: Allows placing resource release code next to the code that acquires it, improving readability.
• Panic handling: In combination with recover, defer can be used to intercept and handle panics.

Example of file release:

// Example of deferred file closing
file, err := os.Open("example.txt")
if err != nil {
    // error handling
    return
}
defer file.Close() // Guaranteed file closure upon function exit

// work with the file