Chap1

Error handling in Go

Errors and error handling are two very important Go topics. Go likes error messages so much that it has a separate data type for errors, named error! this also means that you can easily create your own error mesages if you find that what Go gives you is inadequate. You will most likely need to create and handle your own errors when you are developing your own go packages.

Note that having an error condition is one thing, while deciding how to react to an error condition is a totally different thing. Put simply, not all error conditions are created equal, which means that some error conditions might require that you immediately stop the execution of a programs, whereas other error situations might require printing a warning message for the user and continuing with the execution of the program. It is up to the developer to use common sense and decide what to do with each error value that the program might get.

The defer keyword

The defer keyword postpones the execution of a function untill the surrounding function returns. It is widely used in file inpu9t and output operations because it saves you from having to remember when to close an opened file: the defer keyword allows you to to put the function call that closes an opened file near to the function call that opened it.

It is very important to remember that deferred functions are executed in Last In First Out order after the return of the surrounding function. Put simply, this means that if you defer function f1() first, function f2() second (conceptually, it means defer f1...; defer f2 ... then when the surrounding function is about to return, function f2() -> f1() executes in that order.