Golang Blocks
Go lets you declare variables in lots of places. You can declare them outside of functions, as the parameters to functions, and as local variables within functions.
Note
So far, we’ve only written the main function, but we’ll write functions with parameters in the next chapter.
Each place where a declaration occurs is called a block. Variables, constants, types, and functions declared outside of any functions are placed in the package block. We’ve used import statements in our programs to gain access to printing and math functions (and will talk about them in detail in Chapter 9). They define names for other packages that are valid for the file that contains the import statement. These names are in the file block. All of the variables defined at the top level of a function (including the parameters to a function) are in a block. Within a function, every set of braces ({}) defines another block, and in a bit we will see that the control structures in Go define blocks of their own.
You can access an identifier defined in any outer block from within any inner block. This raises the question: what happens when you have a declaration with the same name as an identifier in a containing block? If you do that, you shadow the identifier created in the outer block.